Engine for Superformance

[Kevin L]

Hi All,
I have not put down a deposit and am simply kicking around the idea so take this question with that in mind. While doing the math to put the car together I am stumbling on what is the correct engine for it. I have commonly owned high RPM cars (M3, S2000, NSX, 125cc Shifter kart, etc); and have little to no experience in high torque lower RPM lump Ford motor. The closest is a C5 ZO6 and a ride in a 04 cobra with the 4.6 mod motor. With that said, I am overly excited about the change. The goal of the car is not really to go for originality, rather fun. I would and have looked at other manufactures but the Superformance offers something to me that I like (roller with dealership near-by to install the engine). So, I understand RCR (looks like a great product), CAV (nice car as well), etc. but this fits me personally better.

On to the car:

MKI body style
Gulf flares
Weber carbs or Weber style FI
Trans: ZF 5 speed
Engine?

Here's my question, what should I even start look at? The SPF dealer pushes Roush and they are nice looking engines, I have looked at Keith Craft and again, nice stuff but to be honest, I am a newbie when it comes to this, I race karts and know very little when it comes to the actual pieces of a Ford engine (never have built or worked on one). So what to look for?

Do I want an aluminum block? It saves about 60# I hear, would I be better getting an iron block and spending the money on the internals so it can be revved freely?
Do I go with a 351W, 351C, 302? I am not sure I really want a 427 in the truest sense, a 351 bored out to 427 might be fine but the more I read it seems like a 351 is the easiest to make power on.
Carb or FI? I am not really a tinker and fix it type of guy, I would rather jump in and drive, is FI better thus should I spend the money on that?

I guess what it really comes down to is price I am willing to spend right and how I am going to use it? Okay then how about 15K for a motor? Is that enough for something that will be reliable and offer some nice power? (flat torque curve would be good I suppose) I took a quick look at Roush and found this crate motor: the 402 IR, it has FI and Weber looking stacks but seems pricy (21K). It will see some but probably little track duty, it is a driver that will be used on the streets to put a wide grin on my face. I like reliability but also want something special, having something with 300 hp is fine but it is a special car and spending a little more to make it amazing is better in my mind.

I guess I just don't even know where to start, is it with the engine size, builder, etc? Any recommendations? As for power output, I think 500+ would be nice. My shifter has a power/weight ratio of around 7.8 lbs/hp, having a car with better would be a nice neck snapping experience.

Thanks for the help

Kevin

 

[Kevin L]

I might have posted this in the wrong forum, Ron could you move it to Engine talk if you think appropriate.

Thanks

 

[Ron Earp]

No problem Kevin, and this is going to be a good one!

 

[DBLDREW]

Well making 500+ on a stroked 351W isn’t that hard. The good thing is that you are in IL so when you register the car it is registered as the year it is supposed to resemble, so it will be titled as a 1966 so emissions will not be a problem. Anyway back to making 500+hp you could go with a 383 - 408 stroker motor. Are you interested in building the motor yourself or are you just looking to purchase a complete package?

If you just want to purchase a complete motor you could buy one direct from ford. They have a 392ci (stroked 351W) that makes 475hp not sure on the price. Or you could check out Keith Craft they have a 408ci that makes 500hp for $5700 or one that makes 575hp for $7400. http://www.keithcraft.com/our_engines.html

 

[DBLDREW]

I was looking on the Keith Craft site again and they have a 331 stroker (a stroked 302 5.0L) that Makes 500hp. There are some pros and cons with the 331. One is that with the smaller stroke you will be able to turn a higher rpm compared to the 408. Now the one thing with the 408 is that it is based on a 351W block, which is much stronger then the 302 block. Once you start pushing close to the 600hp mark with a (non sportsman) 302 based motor it is a ticking time bomb before you will split the block. But the 351W production blocks are very reliable up to 700hp. Not that you need 600-700hp in a car that is that light, but I guess if you need to be even more crazy then 408 will accommodate.

 

[Sandy]

Kevin -

You can make 500+ on a well built 302/331 short stroke motors 8.2" deck. You will spin them relativly high (7-8k Rpm). The trade off really comes down to the driveability and fuel requirements, and you need to figure that out. The small cube motors are also touchy and usually require high compression (11+) to get the power as well as some decent con rods, crank and the often looked over looked valvetrain. The slow (as in RPM only) big cube motors can run on pump gas, have realitivly easy valve train requirements (Hyd roller) and are pretty streetable. I think Keith Craft has a bunch of the Pump gas mosters on his site as well as a few folks here that are of the large cube camp. I personally like the short(er) stroke motors as well. One thing that is also important is making sure your 'propulsion' package is well matched. Make sure you look at the rpm range of your motor, tire/diff/trans to make sure it all falls into place rpm wise. Look around on the engine area you will find a few interesting motor combination that people are using, I think the one that I did (3.25" stroke 347) was compaired with a 427 if similar HP.

If you go aluminum block, add about $4k for block and extra prep required. Also if you go 351W make sure you will have no issues with engine height if you want to run injectors or webers and that the headers are available for you combo.

[Edit] This is the small vs larger inch motor
http://www.gt40s.com/forum/showthread.php?t=17165


HTH

Sandy

 

[Doug S.]

Hi All,
Do I want an aluminum block? It saves about 60# I hear, would I be better getting an iron block and spending the money on the internals so it can be revved freely? Do I go with a 351W, 351C, 302?
Kevin

Good day, Kevin. I see you have many of the same questions I had when I started reading the forum, so here is what I have learned:

Re: aluminum blocks--they are very expensive and do save at least the amount of weight you mentioned over a standard iron SBF, and more than that over one of Ford Motorsports' heavy duty blocks. As I understand it, from reading the forum for a couple of years, losing weight can be a greater help than gaining power (although there have been many discussions regarding this issue for sure!) For my $$, I'm saving up for the aluminum block. I don't think that an iron block would rev any more freely than an alloy block, given the same internal components and build quality.

Re: 302 vs. 351W vs. 351C--IMHO, the 302 block will get you where you want to be, as Sandy and DBLDREW have so eloquently mentioned. I know you can get 351W's to fit, and there is at least one forum member I know of who has a 351C in his ERA kit (my dream build, BTW), but I have taken the good advice of the forum members and decided to go with a 8.2" SBF. I'm going to build a MK I and that is historically the correct engine block, not to mention that most knowledgable forum members advised me that too much cubic inches=too much torque=too much tire smoke in these lightweight cars. Perhaps the best advice I can pass on to you is to match your transaxle to the torque range you are targeting, but save some $$ for big brakes and a good LSD in the transaxle. To quote the member who gave me that advice, "...they'll never catch you". I like that.

Whatever you decide, good luck with your build. Those of us on this forum are all GT40 crazy and most of us believe they are never finished, no matter how good they are.

Doug

 

[chuck smith]

I believe the SPF will handle a big block but if you go with a MK1 body style I would suggest a 331 or 347 aluminum block,weber look fuel injected motor, Keith Craft or George Gessford could build you one of those with top notch internals for well within your budget. A good set of AFR heads and reasonable compression will net plenty of hp. My next choice would be an aluminum block mildly stroked 351w. this engine would probably be easier to drive in traffic with the extra torque. Be careful of over camming whatever you build as a finicky motor is no fun on the street. I have a stroked 427side oiler in my Kirkham 427 cobra,I had a 351 cleveland in my last cobra and now have a Kinetics engineering 302 in my CAV. the 302 is the easiest motor to drive. chuck

 

[Jim Rosenthal]

motor for GT40

These cars don't weigh much, and most of the ZF boxes that we use have a final drive ratio of 3.7-4.2 to 1. Ready for the road, the car might weigh as much as 2300lbs.

I don't think you need any more than a well-built 302 to make these cars perform exceptionally well. I know this has been said before, but they won races at speeds that are still fast today with 289 and 302 engines. The components they had were no better than we have today, and in some cases not as good.

A really hot motor (a 351 or bigger) will get you a lot more power, but it may not make your car any more fun to drive, or even that much faster. What it WILL do is wear everything out a little quicker, and cost you more both to maintain and buy in the first place.

What I think is the ideal engine for a GT40 is 350-400hp, and a nice broad torque curve that allows some flexibility- assuming you are going to drive your car on the street. There is nothing more miserable on the street than a peaky, temperamental engine that is ill-tempered and balky below 3000 revs and then turns the car instantly into an animal at 3100. That is not what I want in my car.

The best thing about modern engine building is that you can get an EFI system that will give you a smooth idle, a broad torque curve, good power up to 6500 revs, and the ability to drive flat out on the race course or in traffic equally well. What that adds up to is getting the most use out of the car you've spent all this money to acquire. Now, if you want to only race the car, your uses are far different- but very few of us if any are in that situation. Virtually ALL these cars are going to be driven on the street 99% of the time. And they should be. I think the most intelligent use of your money is in a 331 stroker or a 302 with the best engine-management system you can get, which I suppose is a Motec/TWM system.

This is probably a bit heretical to say, but when I went to the engine builders to discuss what I wanted, I told him that what I wanted was the same feel, if they could do it, as the 3.4 liter V8 in my Ferrari Mondial- very responsive, revs like crazy, good power from 1500 revs on up, and not peaky. That car has 300hp in a car that weighs 3400 lbs. 1149 will have 360 hp in a car that weighs 2200.

Can't wait!!!

 

[Mark Worthington]

Re: aluminum blocks--they are very expensive and do save at least the amount of weight you mentioned over a standard iron SBF, and more than that over one of Ford Motorsports' heavy duty blocks. As I understand it, from reading the forum for a couple of years, losing weight can be a greater help than gaining power (although there have been many discussions regarding this issue for sure!) For my $$, I'm saving up for the aluminum block. I don't think that an iron block would rev any more freely than an alloy block, given the same internal components and build quality.

I'll second what Doug (and CHuck) said. Saving that 60 pounds of weight is like adding 20+ hp and it pays additional dividends in handling and braking. I would do a 331 to keep the rod ration within reason, use solid lifters to let it rev right up to 7,500 rpm, and I'd go with stack EFI and a cam designed for a flattish torque curve. I think such an engine could easily make north of 425 hp and still remain street friendly. The higher the rpm, the better the car will sound through a crossover exhaust.

 

[CliffBeer]

These cars don't weigh much, and most of the ZF boxes that we use have a final drive ratio of 3.7-4.2 to 1. Ready for the road, the car might weigh as much as 2300lbs.

I don't think you need any more than a well-built 302 to make these cars perform exceptionally well. I know this has been said before, but they won races at speeds that are still fast today with 289 and 302 engines. The components they had were no better than we have today, and in some cases not as good.

A really hot motor (a 351 or bigger) will get you a lot more power, but it may not make your car any more fun to drive, or even that much faster. What it WILL do is wear everything out a little quicker, and cost you more both to maintain and buy in the first place.

What I think is the ideal engine for a GT40 is 350-400hp, and a nice broad torque curve that allows some flexibility- assuming you are going to drive your car on the street. There is nothing more miserable on the street than a peaky, temperamental engine that is ill-tempered and balky below 3000 revs and then turns the car instantly into an animal at 3100. That is not what I want in my car.

The best thing about modern engine building is that you can get an EFI system that will give you a smooth idle, a broad torque curve, good power up to 6500 revs, and the ability to drive flat out on the race course or in traffic equally well. What that adds up to is getting the most use out of the car you've spent all this money to acquire. Now, if you want to only race the car, your uses are far different- but very few of us if any are in that situation. Virtually ALL these cars are going to be driven on the street 99% of the time. And they should be. I think the most intelligent use of your money is in a 331 stroker or a 302 with the best engine-management system you can get, which I suppose is a Motec/TWM system.

This is probably a bit heretical to say, but when I went to the engine builders to discuss what I wanted, I told him that what I wanted was the same feel, if they could do it, as the 3.4 liter V8 in my Ferrari Mondial- very responsive, revs like crazy, good power from 1500 revs on up, and not peaky. That car has 300hp in a car that weighs 3400 lbs. 1149 will have 360 hp in a car that weighs 2200.

Can't wait!!!

Hi Jimbo, I also have a ferrari Mondial ('88 3.2QV) cab and love it as well but it doesn't come anywhere close to my CAV with a 350hp 302. I think the difference being (other than high torque for the CAV and high hp for the ferrari) the weight - 2,300lbs for the CAV and about 2,850lbs for the Mondial. That weight delta makes a major big difference in performance. But, with the Mondial I can pull up at the restaurant with the wife and kiddies in back, top down, and, get the primo valet parking right in front - that's fun. Perhaps the most joy comes from the variation between the two but both will get you down the road pretty quick!

 

[Sandy]

Before this becomes Ferrari Chat, feedback from Kevin would be in order

It sounds like what Kevin wants (from his comments ... shifter carts, etc) is more of a race treatement vs. a car to pick up the kids from school in. One of the hardest part of the build, picking really what you want to do with it.

Carb (Non Weber) vs EFI, again depends on what you might want to do. The EFI will be more time consuming to get running from scratch (plumbing, electrical, and least of all tuning), looks cool, but in the long run I really can't see why people think it makes such a huge difference. EFI definitly has the look over the carb. I have a TWM injection for my car, and it will only likely find its way on the car after I have nothing else to do to it or pump the rods out the side and do a rebuild. The carb is pretty simple and lacks no ability to make power and still has good drivablity, just does not look at hot as the stacks.

Too much coffee this morning, sorry for the ramble!

Sandy

 

[Kevin L]

Feedback and more questions

Feedback, okay where to start. I am on my lunch break so if I don't get through all of it I will get back later

First off, thanks all for the help, I cannot tell you how appreciative I am.

DBLDREW - I have a great desire to build the motor myself but am realistic in that I have A) No knowledge or experience B) Not enough time
So a complete motor is my best bet. In addition I will probably have a mechanic or the Superformance shop put the car together for me.

The 408ci with 575hp sure looks nice; would that fit in a Superformance? One of the problems I am having at this point is just getting some concrete specs for the car; anyone have that? I should ask the dealer but they did not seem to have a lot of info. The MKII that was there (pictures are on the forum) did not have an engine in it and I did not want to take measurements as it is someone else's car.

Sandy and DBLDREW - about the 302/331, I like the idea that it is period correct for an MKI but your comments about a 500+ 331 being less reliable and less drivable worry me a bit. I think some of this worry is that I have no exp with one of those motors so I do not have a benchmark of what drivable is. As an example, my M3 rides really well to me, most other think it is rough, but I came from an S2000 that was really rough, that’s my benchmark. I have no benchmark for a 408 vs. 331. Would a 500HP + 331 really be as peaky as some are eluding to? E.g. Sandy, if I built you’re motor a that you linked too but a bit detuned, is that going to be tough to drive on the street? Your RPM range comments worry me a bit as I again have little knowledge of that. Any ideas of where to start learning about RPM range for trans/tire/diff and a high vs. low rpm motor?

Doug - Glad to know I am not the only one learning here! I like the idea of aluminum a lot as well, just not sure what to do yet. An LSD is critical in my mind so that will be added, as for the brakes, I hear it comes with Wilwood brakes, I am guessing based on their performance videos these should be enough at this point. Excellent point on the too much cubic inches. In reference to the rev freely, I was wondering if I spent more on internals in the non-ally block than the budget would allow for an ally block if that would be better. I agree that the same internals they should rev similar.

Chuck - What made the 302 the easiest or easier than the 351C?

Jimbo - I understand your point on performing with 350-400 hp and that should be enough, I am still deciding on that, but point taken. This one will be driven on the street 99% of the time, so EFI is interesting.

Sandy, it will be raced but not much e.g. 4 times a year at track days but I am really struggling with what I want the motor to do. There is a certain satisfaction to a high revving motor, the shifter kart is a dog below 8K but from 8-14K it is a beast, it is best to hold on during the transition; but, that would not be fun on the street. My M3 and aforementioned S2000 and NSX are no dogs in the lower RPMs, 4K and below (S2000 6K and below), but they do pick up their power significantly above that threshold. If I had a motor that I had to keep at 3000 and above for max power I would not mind, it just can not have an on off switch from 2900 to 3000 as I would want to cruise around town at a reasonable level. I think the hardest part about this is distilling people's comments of what is drivable vs. what is not without ever having the first had experience of it. Maybe I should attend an event or two first

I think so far I have learned this:
LSD is a must;
Leaning toward a 331, 347 (are those stroked 302s?) but a 408/410 is still sitting out there
aluminum block is still debatable for me (will come to budget);
EFI probably;
stacks definitely;
will order it from a builder like Keith Craft;

When you order a motor like this, does it come with everything or will I need to add more bits to it? I suppose this has to do with how it is ordered? To build on this has anyone else built a Superformance (Cobra or GT) and beyond the engine and trans what other costs do you need to account for? Plumbing? Oil cooler? Erroneous fasteners?

Finally, is it possible for all these motors to idle a bit rough? I love that sound (based on this comment in addition to the rest of the post it should illustrate lack of knowledge)

So with that input, any other comments that will put me in the right direction? This seems a bit overwhelming, hope I did not ramble too much.

Sandy, you have a PM

 

[Kevin L]

One more option

Looked at Keith Craft again, what would I be doing wrong if I just went this route?

Keith Craft
331/347 standard crate engine
500hp
470 ft. lbs. of torque
$6,295.00
Found here: http://www.keithcraft.com/ads/index.html#3

Put on EFI with a good engine management system and and ally block. That should stay within the budget, correct? Suggestions?

I just spent my lunch break and half the afternoon on this, suppose I should get back to work.

Thanks again
Kevin

 

[Doug S.]

Good choice, IMHO!

You would not be doing anything wrong, IMHO--in fact, you just might be the envy of a majority of our forum members. I would highly recommend spending the $$ for the alloy block (as I understand it, the cost jumps by about $2K with the alloy block), and with the extras you mentioned you would have a period correct looking motor that will deliver not only good power and torque but lighten the rear end of the GT as well. Not much to argue with there!!

Now the only thing you need to decide on is the displacement. As I have been investigating this issue, I notice Dart offers an alloy block with a larger bore--I think it comes already at 4.125", but it can be bored to 4.2". With a bit more bore than the 4.125" you might get closer to the 347 CID with only a slight stroke increase on the crank, which will help with the upper RPM limit and also help keep the piston pin away from the oil ring land. You can bet a paycheck that Keith Craft can advise you better on this issue than I can, so when you contact them you might want to check this out.

However, in one of my threads, one of our members who is a highly regarded engine builder made the following suggestion: "While looking for your Dart Block check out the 8.700" deck option. Use the 3.25" stroke crank and any bore you fancy up to 4.200" ( might pay to use say 4.170" just in case you love driving the car enough to wear out the first bore!!). The Taller deck would allow longer rods for a better rod ratio."

I'm not sure what other issues you might face using the taller block rather than the standard 8.2", but if you really want a high revving motor this might be a factor you need to consider.

Doug

 

[DBLDREW]

The 408ci with 575hp sure looks nice; would that fit in a Superformance? One of the problems I am having at this point is just getting some concrete specs for the car; anyone have that?

The 408 is a stroked 351W motor and it is just slightly larger then the 302. So I would be extremely surprised if it doesn’t fit. The motor mounts, bell housing etc. are the same, the only difference is the deck height is taller.

Sandy and DBLDREW - about the 302/331, I like the idea that it is period correct for an MKI but your comments about a 500+ 331 being less reliable and less drivable worry me a bit.

The reliability of the 302/331 really won’t be a problem, unless you feel the need to modify the car to make over 600hp. If you keep it at the 500 mark the motor will hold up fine. That is if you keep with the standard production block (which is what they are using) But if you go with an aftermarket block like the ford sportsman block or a dart block you will have no problem pushing it past 600hp. Now you also mentioned going with an aluminum block which I believe will also be able to push past the 600hp mark (double check because I’m not sure on the aluminum blocks!) But realistically unless you are making a 100% track car 600hp in such a light car would be a bit of overkill, to say the least.

Now the drivability of the 331 shouldn’t be a problem. It is listed as “pump gas” so it will have a streetable compression ratio, so you can run 91 octane. The one thing you will run into is that it will have a pretty rowdy camshaft. So you will have a pretty rough idle, (which I think sounds fantastic). But this will lead to some driving issues. With my car that has a pretty aggressive cam it just doesn’t like driving under 2000 rpm. It idles fine at around 1000 rpm with a nice lope to the idle. But when I’m driving and the revs drop under 2000rpm the car starts to buck and surge. If the revs are over 2000 it’s butter smooth. So you just have to make sure you keep it in a gear to keep the revs over 2000rpm (which isn’t that big of a deal)

 

[Jac Mac]

302 W CID Combo's.

Kevin;
You may be getting confused with all the capacities being talked about here.
331 is 4.030" bore x 3.25" stroke in 8.200" deck block. Std + Ford 302 Block
347 is 4.030" bore x 3.40" stroke in 8.200" deck block. " " " " "
348 is 4.125" bore x 3.25" stroke in 8.200" deck block.( Dart Iron/Alloy)
364 is 4.125" bore x 3.40" stroke in 8.200" deck block. " " "

Now to add to the mix; All of the above in kit or crate form use a 5.400" long connecting rod.

With the 3.25" stroke this give's a rod ratio of 1.66 to 1. On the 3.40" stroke it gives a rod ratio of 1.59 to 1. While this brings a lot of factors like bore wear ,friction etc, into play the biggest difference is in the way you, the driver will notice it. The 3.25" stroke versions are quite happy to rev up to 7/8000 rpm while the 3.40" stroke gets quite harsh or mechanical above 7000 rpm. In a car like the GT40 I feel the shorter stroke versions are more suited.

The DART block is also available in 8.700" deck height, but this means longer push rods , wider valley cover etc which pump the $$ factor up real quick.

The DART Block can go to 4.200" bore if reqd.

Jac Mac

 

[chuck smith]

I like the sound of that 348. The 351c is a neat motor,however parts are harder to find and expensive. It is also bigger than a 351w and headers are hard to find. Stick with a 302 or 351 based motor. an SPF will hold a 427 FE,so it will fit a 351w no problem.

 

[Alex Hirsbrunner]

Also note that World Products offers a 8.2" deck height block with 351W oil pump and distributor locations (known as their "C" block), allowing for a 371 CID (4.125" x 3.470"). Like a Dart, this can go out to 4.200".

Al

 

[Doug S.]

I like the Cleveland, too!

I like the sound of that 348. The 351c is a neat motor,however parts are harder to find and expensive. It is also bigger than a 351w and headers are hard to find. Stick with a 302 or 351 based motor. an SPF will hold a 427 FE,so it will fit a 351w no problem.

Chuck, I, too, like the Cleveland style motor very much and I agree with you on almost every point, with the possible exception of the difficulty finding good parts! Thank goodness our friends down under had more time with the Cleveland design than we did here in the U.S.!

Want a new alloy Cleveland block with priority oiling, thereby eliminating the main bearing oiling problems production Cleveland blocks have? Check out this website: http://www.sjperformance.com.au/ They advertised an all alloy Cleveland block at one time, but I didn't take time to check it out for this post, just C&P'ed the URL.

Want some awesome heads and an equally awesome intake manifold to feed the monster? Check out the Chi heads at these websites: http://www.chiheads.com/
http://www.chiheads.com/our_results.php

Notice that both businesses are located in Au.

Want a Weber look-alike EFI setup for your 351-C? Check out what these guys offer: http://injectionperfection.com/

So, the parts are out there to build a mondo Cleveland, they are just expensive (you were right on on that one!) and on the other side of the world for the most part.

In my dream world, this all aluminum Cleveland would be my choice for an engine for my GT40. Unfortunately, reality sets in and I, like you, like the 348. The CID is high enough to take advantage of the flow characteristics of a good set of alloy heads and with the .25" additional stroke the crank is still "short" enough to allow high RPM's with a good reciprocating assembly. IMHO, it seems to be the best combo. Mine will have Cleveland heads, if I can source a Track Boss manifold somewhere to complete the conversion to "small port Boss 302". Oh, yeah--the Chi heads people offer one of those, too, but it looks like quite a high riser and with a good carb I think it would interfere with the back window!

Many thanks to Dave Wharren for his information regarding the Cleveland sources I mentioned (and for his incredible ERA build photos) and to Jac Mac for his valuable knowledge--I find myself constantly going back to their posts for useful information.

Doug