Noob Motor questions

Have a SPF GT40 on order.

The GT40 is primarily for trackdays will also prob move from track to track on a trailer so I can have good ride height, wheels tires jack brakes etc on hand.

Would love advice on motor choices. I see many if not most have apounched out 351/427 combo. Is this a good motor for the track or is it overkill?

I have looked at 302 based motors. It seems the choices these days are a 331 or 347 with same crank as 331 but bigger bore, or the motor du jour of a 363.

It seems pretty much every hyd lifter mtor is limited to 6500 rpm?, where as a solid lifter can comfortably go to 7500. For the track is 6500 a limitation, is it better to go with a higher redline. Does anyone have experience with a 363, it it a fast spinner or a rough engine. It seems that a good 363 motor even with hydraulic lifters is 520-540 hp and 480 ft lbs on pump gas. A big bore 347 with short 3.25 crank is perhaps 20-40 hp less. Does it really matter in a car so light.

Alternatively is it wortwhile going for a high rev race motor?

Is it even worth going with a 302 based mtor or should one just do the 427W.

Thoughts on carb Vs injection? and suggestions on engine builders.
I have looked atr Keith craft, Gordon levey and Benett racing so far.

Since it takes SPF almost a year these days I still have lots of time to figure it all out, but would greatly appreciate opinions from those experienced.

car will do 80% track and maybe 20% street.
 
Re: Noon Motor questions

Sean - Welcome to the fold. As for the engine choices, it depends on what you're looking for; longevity, etc. For a 302 block, I think, and the guys at Keith Craft also stated, the 331 will be a longer lived engine than the 347 if you're running it hard. They told me there was no problem with the 347 if you intend to 'freshen' it periodically. The 347 rod angularity and ring/pin issue exists but they seem to do OK. You will lose a small amount of torque with the 331 but not a major problem. If you go with the larger, 351 based Windsor, it seems the 408 combination is a winner, Lots of torque, free revving, good longevity. You won't need to rev any of these too high and 6200 or so out of a hydraulic roller cammed engine will provide more than enough to get the job done, without the potential for wear and damage that could accompany the higher revs. The car is so light the performance will be more than you need. You will need to concentrate on driving skills and may not use all the power on tap for quite a while. Watch some of the videos and you'll see these drivers go through many of the turns at fairly low rpm with no problem accelerating on the exit.
Fuel injection is great if you don't mind the set-up work and this will allow you to fine tune the engine at any point in the range. It can involve a bit of work and you should line up someone who is well versed with your chosen system for assistance. Carburetion is simple and will provide the most horsepower at the top end. I'm waiting for al the F.I. guys to protest that but it is true. F.I is a better delivery system but carburetion is a better emulsion system and is proven to nudge out F.I. at top revs. However, carburetion is not a 'fits-all' system in that it can't match F.I. at meeting engine needs at ALL points in the range.
You will also need a transaxle that will handle that torque if you go for the larger block. The G-50 and the Audi will be Ok for the small block but you'll have to opt for the ZF/RBT or similar for the larger engine. For track use, you will need a durable limited slip differential set-up too. In short, you won't be concerned about having enough power for quite some time, if ever. Your budget should include a good sum for tires, even with the 'small' engine.
Engine builders vary but I would not hesitate to get one from Keith - very thorough and they will talk to you no matter what the question or issue. Also very experienced and a good reputation. Stay away from T&L, based on feedback and only buy from a builder who will really dyno test your engine before delivery. If it does the grenade act, HE is on the hook, not you and knowing that, he's not going to give you a substandard product.
Above all, get a few opinions and make an informed decision - you have some time to think about it.
 
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Re: Noon Motor questions

.....Just an update.....T&L are no longer a viable company. I beleive they shut their doors some years ago after the reported financial problems.
 

Howard Jones

Supporter
Re: Noon Motor questions

For track use: in order of importance

1. Tires. If you run Hoosiers then 8in front wheels and 10inch rear will let you run 245.40.17 and 315.35.17s. This setup will give you huge grip. Way more than enough to run in the fastest group that your open track group has. I see NO reason to use 15 inch diameter wheels other than historic looks. Be aware that if you want to run street tires at some point there just are not any good ones in 15 inch except Avons. Big$$$$ for them.

2. Transaxle. Porsche G50 01-03 with a stronger side diff cover, G50-52, 930, or a RBT/ZF would be my choice. There are others out there, I just don't have any experiance with them. I wouldn't spend that much money on a SPF and use a Audi or Renault. Gear them for 175MPH @ 6500 in 5th. I regeared mine with a 2.30 1st and spread the other 3 out with a 1 to 1 4th and a .85 5th. These choices are good to 500HP if you drive it like it's your money. Beyond 500Hp I think you should be talking to racecar builders about modern racing GRBXs. Use the really good CV joints. The GRBX vendors can talk clutch and CV joints with you.

3. Limited slip. Absolutely a MUST HAVE! I like the Torque Biasing type like Quaife but others types do work well. Theres no point in running on track without some form of LSD unless it's simple parade lap stuff. Anything over 300HP at the wheels and I would go so far as to say its a requirement on any GT40, even a pure street car.

4. Brakes. Put as much brake on the car that will fit in the wheels and take the time to really balance them front to rear while at race speed. Start slow and work up to full HARD stops from 80-90MPH. Find a good place to do this without curbs, fences, or trees, I did mine in a Mall parking lot early Sunday morning one time. You can get the 12.3 X 1.25 Wilwood curved vane two piece rotors into a 17 inch wheel with plenty of room to spare. Their forged Super light 4 piston calipers are enough caliper. You can start with the track/HPstreet pads and work up to Bs and Cs as you get faster. Have a look at Wilwood's website. Other noted manufacturers such as Bremo and Alcon are good also. Just don't skimp on brakes. This is another reason to run 17s.

Last. Engine power. 300 Hp at the wheels is just enough to run with the fast group........but just. You will really need to make time in the brake zone and in the center of the corners. 400Hp is plenty.........really. More than 450-475 (we are talking real race slicks now not DOT radials) and IMHO Most people who are amateurs like me wouldn't be able to use it all........get pro driving training. 500+ ......humm....... X pro racers maybe but if someone wanted to GIVE me a 500-600hp motor I wouldn't put into my car.

I think you would be fine with a Hyd roller cam, 331 @ 10.5 to 1 compression ratio (pump gas baby!). 6500PRM motor. I like the Edelbrock alum RPM performer heads with the 2.02 intakes. The intake runner volume is right at the top end of what will work at 2700-4000 RPMs without giving too much low end torque away for High revs HP (>7000). Good compormise for a open track car. I would guess you would be right at 370 Hp at the wheels and about 425 crank with a Hyd roller 280-290 duration cam @ about 450inch lift. Good 3000-6000RPM power and will pull well down to 2000. Perfect for a fun track car.

Last word: "There have been a lot of really cool hotrods fucked up with too much power" I forgot where I heard that, but never has a truer word been spoken.
 
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Re: Noon Motor questions

Howard, I could read your posts all day long. Anyone reading them would know you speak from experience and thats a beautiful thing IMO. The post above is some real good S**T and words to live by.
 

Howard Jones

Supporter
Re: Noon Motor questions

Jimmy, well I only know what I know, it may or not be right for that matter. But if you get several of us all saying the same thing then at least you have a pretty good direction to focus your attention. There is a huge amount of talent on this website. We should all remember Ron for what he has done for all of us.

Questions like this one on engine choice are answered in the end by what works for each guy. The best we can all do is try and help someone avoid a known issue and maybe save someone a little money and grief.
 
Re: Noon Motor questions

I totally agree with Howard's comments on the 331 & spec. given. I will note that a mildly modified 302 with a carb is also a very good street engine. Only use EFI if you choose to spend the money. Built a BUNCH of Cobra replica's with similar engines.
The 347 seems to be a hand grenade when run at high RPM's. Seen several fail.
 
Re: Noon Motor questions

Thanks for all the great advice. I do have quite a fair amount of track experience as I raced skip barber single seaters and then spent the last few years fun tracking my lotus elise, which has suspension brakes and yoko slicks, but the bone stock mtor.

So lets say I learned how to corner on a lowish powered car, and even then the 195 hp lotus can put out too much power if you put it on too quick on at the limit or on a tight bend. What the lotus lacks is drive out of corners and its just weak on any larger Hp track. Once you get near the bends though nothing really comes close, even full on track prepped cars. I

I am planning on/hoping to keep the lotus for beginning of the season dialing in, tighter tracks like LRP, noise restricetd days, and driving the twisty streets near where I live.

The Gt40 will be for bigger tracks so I can better dispatch with newer vettes porches etc. I like the idea of running slicks, seems like a must. Some seem to suggest that there is an avon race tire in 15 in that is also really good, anyone have any experience here, also what size wheels do you use for say a hoosier.

On the motor front you can do a 347 two different ways, one is the long stroke with 3.4 crank, the other is to bore the block(aftermarket boss or dart) and use the same 3.25 crank as a 331, which seems like a really neat option as you have the short crank from a 331 with just a little more go.

I also see that one can get a hi comp 331 from ford racing that spins to 7k but that requires race gas, no prob at the track or for limited street use, but it can be a drawback. So maybe one gets a similar effect with a short stroke (3.25) 347 and pump gas. Maybe even go for solid lifters so it can rev, or is extra revs just a waste, is 6500 plethy for track woirk or do you ever wish for more revs. There is also now a 363 which has the 3.4 crank and the big bore with the light low 8.2 block.

Some people say that the newer 347 with 3.4 crank is a stout motor, that the problem was always piston rings with the bbig bore an this is now solved. Othrs say that the rod ratio of a 3.4 crank is too poor for a long lasting motor. If you saw a 347 blow was it an older motor, what blew.?

So my thoughts are short(3.25) stroke big bore(4.15) 347 with hydraulic or solid rollers? or a 363 with hydralics, assuming a 3.4 crank motor can hold up these days. That way i get the benefits of a 302 style motor with some serious go for the street enviroment without going overkill on a 427.. One other requirement is that the motor just be smmooth at revs, there is a difference between a motor that can rev and one that likes to rev. All opinions appreciated. Also anyone have experience with 331's and 363's, also solid lifetres how often do they need adjustement.

The of course for similar money you can get the 427 but it seems from those who track that this is overkill. Also from what I understand you can HSR race a spf Gt40 if it has a 302 block.

Any thoughts on roll bars and cages.

The advice on gearing is huge, had not thought it through before and obviously the gearing and power charateristcs should match. Planning on a RBT so the tranny should be strong enough.

On the track is 6500 revs plenty or do you sometimes wish for a motor that can stretch further? Has anyone seriously tracked a 427 car, my fear is you end up with a car that is all axe and no rapier just relying on lugging power and too much torque comming out of bends, but then these same power charateristics can be fun on the street. Lastky I hear that the smaller motors witht heir lower rotational mass just spin up much quicker?

As to brakes I think one is somewhat limited with a SPF car, I have found using pagid rs14's and really high temp race fluid to do the trick in the lotus, but perhaps this is not enough here?

I already run in the top class at the track in my little lotus, so I am hoping the SPF will eliminate the speed deficit on the straights and drive deficit out of bends whicle being pretty close to the lotus on corners. At roughly 2300-2400 lbs the SPF is say 400lbs heavier than the lotus but otehrwise should be good at corners as it has decent suspension? and a lot is down to tires and brakes.

The alternative is to go dodge viper or supercharge and intercool the lotus to the nth degree(taking away its inertia driving experince), everything else is paddle crap which has no appeal.

As I will be 50 its probably going to be my last hard core car, and a realization of a 30 year quest to have a GT40. So while its not $$$ unlimited i do want to do it right.
 
Re: Noon Motor questions

"If you saw a 347 blow was it an older motor, what blew.? "
Yes twice, in fact. Older motors with the 3.4 crank. Rods gave it up in both. One holed the block at 6800-7000 RPM (best guess). Both of these engines had run at high RPM for several hours over a few sessions.
 
Re: Noon Motor questions

You may be over-analyzing this. As most of us have said, stick with the 331 with around 425-475 hp, use good tires, race type brake linings, a good limited slip diff, and go at it. Getting used to the horsepower and traits of the 40 will keep you occupied - you won't be thinking about how much horsepower you thought you needed. Attached is a representative set-up for a 331 SBF.
 

Attachments

Re: Noon Motor questions

My choice would be a stock block/stroke 302/289 ford with a decent forged crank,rods,pistons with internal balance, dry sumped ,solid roller cam, decent heads, lightweight valve train, throttle bodies and programmable ecu, wasted spark, and assemble by someone that can use a spanner . You will see the perfect track day 450 + hp 7500 + rpm screamer. If the budget can stretch to it use a dart or motorsport block Built like this back in their day they surprised the world , now with all the fancy heads and induction systems about they still are. Great little engines let them rev sod the strokers:lipsrsealed:

Bob
 
Re: Noon Motor questions

My choice would be a stock block/stroke 302/289 ford with a decent forged crank,rods,pistons with internal balance, dry sumped ,solid roller cam, decent heads, lightweight valve train, throttle bodies and programmable ecu, wasted spark, and assemble by someone that can use a spanner . You will see the perfect track day 450 + hp 7500 + rpm screamer. If the budget can stretch to it use a dart or motorsport block Built like this back in their day they surprised the world , now with all the fancy heads and induction systems about they still are. Great little engines let them rev sod the strokers:lipsrsealed:

Bob
I hear you. Yes the budget will stretch to a dart block so will prob go for a bored 302 and short stroke, that way i have some ccs and rev/reliability. In terms of forged cranks and rods most seem to offer scat, are there better/lighter alternatives, also what is used to make up a light valvetrain?

If one is going for a revy motor, what type of adjustment do the rockers need, is it complicated and how often.

Seems for power its hard to beat a 4 barrel.

Def going to do a drysump. I want my motor to be strong smooth and last. Blowing amotor on track ruins the day, puts oil down which is a danger to you and others.
 
Re: Noon Motor questions

You may be over-analyzing this. As most of us have said, stick with the 331 with around 425-475 hp, use good tires, race type brake linings, a good limited slip diff, and go at it. Getting used to the horsepower and traits of the 40 will keep you occupied - you won't be thinking about how much horsepower you thought you needed. Attached is a representative set-up for a 331 SBF.

I hear you. BTW do a lot of driving at LRP.
 

Howard Jones

Supporter
Re: Noon Motor questions

So a follow on: Tires. These cars will take a few days worth of set up R&D at the track to get it just right. That's just the way it goes. So I would buy a set of R6 Hoosiers to do the first season or so. That would be about 4 or 5 weekends for me. They will last that long. Then the following season go to real race slicks IF you need to go faster. I have been led to believe that a Dunlop race slick can be 4-5 sec or more a lap faster than the R6's on a 1.55 lap. That's a lot.

As far as the Avon's I mentioned go, I was referring to a pretty good street summer max performance tire that is available in 15 inch. They do make race slicks I just don't know anything about them.

If you do build a motor that is not a pure race engine (pump gas motor) then I would build a hyd roller cam engine because the oil available nowadays is pretty much no good for flat tappet cams. Google ZDDP oil additive and you can read all about the problem. Hyd roller lifters are heavy and so they limit engine revs to about 6500 RPMs and with the compression ratio held to pump gas specs of about 10.5 to 1 you are again not going to be making any more power at about 6000 RPM. Look at the above dyno chart.

By the way that engine is Perfect for a ZF and a GT40. Just do that. I bet that combo would last 10 years + with oil changes. Not stupid money either.

I didn't mention Webbers or 8 stack FI before. People who want them do it and deal with the setup. No real difference in lap times over a 750 DP Holley but way better to look at. If I had the extra $$$$$$$$$ I might do the FI thing but it's all going into the SLC.

If you run you lotus with a fat passenger and full tanks then you are near to the weight of a track only GT40 with one session of gas and one seat in the car. So think your lotus with double ++ the power and 1-2 inches of additional tire width.
 
Re: Noon Motor questions

Howard - That motor in the dyno chart is an upgrade from the standard Keith Craft crate engine with street civility in mind. It had a 1" 4 hole carb spacer/isolator added after delivery from KC (on their advice) for a bit better mid range response. It has a Canton 8 qt road race baffled oil pan, MSD ignition, 10.1 comp ratio, forged pistons, Scorpion roller rockers, steel crank (balanced assy), TFS hyd roller, and Edelbrock Performer RPM intake on AFR aluminum heads. I included this info for perpective on a comment on the carb you mentioned. I think the 750 Holley would be a bit much unless you swapped out the cam for a more agressive one. This engine has a Quick Fuel 680 and the carb, the manifold and the heads will all flow more than the engine used at peak hp/rpm according to the flow numbers and efficiency info furnished by KC (which I didn't post). Just a switch to a different cam, using all the existing components will net an increase, making a 750 cfm carb unecessary. In fact, you might soften the low end response without appreciable high end gain. With a nasty cam in there and possibly an Air Gap or Victor manifold the big Holley would work well but you will lose some streetability. I thought the engine was a good deal at $8400, w/break-in and dyno test. Some might disagree I suppose. As you said, not 'stupid money' and it will have the minimal maintenance longevity you mentioned. Thanks for the 'perfect engine for a GT40' comment. I talked this over at length with the folks at KC...car weight, intended use, etc and this is what they came up with.
A.J.
 
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Re: Noon Motor questions

So a follow on: Tires. These cars will take a few days worth of set up R&D at the track to get it just right. That's just the way it goes. So I would buy a set of R6 Hoosiers to do the first season or so. That would be about 4 or 5 weekends for me. They will last that long. Then the following season go to real race slicks IF you need to go faster. I have been led to believe that a Dunlop race slick can be 4-5 sec or more a lap faster than the R6's on a 1.55 lap. That's a lot.

As far as the Avon's I mentioned go, I was referring to a pretty good street summer max performance tire that is available in 15 inch. They do make race slicks I just don't know anything about them.

If you do build a motor that is not a pure race engine (pump gas motor) then I would build a hyd roller cam engine because the oil available nowadays is pretty much no good for flat tappet cams. Google ZDDP oil additive and you can read all about the problem. Hyd roller lifters are heavy and so they limit engine revs to about 6500 RPMs and with the compression ratio held to pump gas specs of about 10.5 to 1 you are again not going to be making any more power at about 6000 RPM. Look at the above dyno chart.

By the way that engine is Perfect for a ZF and a GT40. Just do that. I bet that combo would last 10 years + with oil changes. Not stupid money either.

I didn't mention Webbers or 8 stack FI before. People who want them do it and deal with the setup. No real difference in lap times over a 750 DP Holley but way better to look at. If I had the extra $$$$$$$$$ I might do the FI thing but it's all going into the SLC.

If you run you lotus with a fat passenger and full tanks then you are near to the weight of a track only GT40 with one session of gas and one seat in the car. So think your lotus with double ++ the power and 1-2 inches of additional tire width.
What size wheels go with the R6 and slicks? I hear you on starting with some resonable tires first and getting to knwo nthe car.

On the motor my thoughts go to a dart block with a 4.125 bore and the short stroke 3.25 crank from the 331, this setup yeils 348 Ci. The bauty is you have the short stroke crank from the 331. I would rather soend ny money this way than all the extar for injection, maybe even stretch to a aluminum bock and save another 80lbs or so.

As to cam, I dos ee the value in hyd roller. One can also doa solid roller. My thoughts re if all that os required every eyar is a valve lash that might be ok to gain an extra 740 rpms. the motrs I see with solid roller seem to make the same power just for much longer.

Maybe its my Lotus background but lighter and some revs so you dont need to shift so often seems like an idea. But then a GT40 is such a different car maybe I am looking for DNa which is not there.

BTw I know back in the 60's a GT40 had 380 hp an dlater maybe 420. What type of revs were they running
 
Re: Noon Motor questions

Been involved with a motor as you describe above for the past 10 or 11 years , but with a solid roller. Motor has been rebuilt/freshened twice in that time, both due to outside influences/ people creating an issue.
It does approx 1000km a year of practice/racing.
Runs to 7800 RPM ( Limiter ), can go higher but that would require a lighter valve train & more frequent maintenance. On the above basis it has reqd a new timing chain & valve springs every 3000Km approx.
 
Re: Noon Motor questions

Been involved with a motor as you describe above for the past 10 or 11 years , but with a solid roller. Motor has been rebuilt/freshened twice in that time, both due to outside influences/ people creating an issue.
It does approx 1000km a year of practice/racing.
Runs to 7800 RPM ( Limiter ), can go higher but that would require a lighter valve train & more frequent maintenance. On the above basis it has reqd a new timing chain & valve springs every 3000Km approx.
So in other other words not really useable as I do 3k km per year. Better go then with a bigger motor less revs and hydraulics. .
 
Re: Noon Motor questions

Initially the motor was built with individual rocker arms/studs/guideplates, that was where the 'people' problem crept in as the guy/s that travelled with the car were not confident in setting valve lash etc, once a set of paired shaft rockers were installed the valve train remained stable with lash only being checked as a means of detecting any problems in the valve train, on that basis I would think that the engine would be suitable for what you describe, particularly when you consider that our car was only used for one month of the year, more damage etc from corrosion occurred due to the extended layoff than what would have occurred if the car was used on a more regular basis. I hope you intend to check valve lash & cut open your oil filters on a more frequent basis than once per year, those two checks alone will save you thousands if you are unfortunate enough to have something start to fail in the valve train or oiling system. I dont like hydraulics as if you 'wrong slot' a downshift & let the clutch out you will pump up a lifter, all the rev limiters etc in the world wont prevent it, plus if you have a good 'ear' for mechanical noise you might hear an increase in valvetrain noise, with the hyd lifter any failure process will be well underway by the time you hear it.
 
Re: Noon Motor questions

So in other other words not really useable as I do 3k km per year. Better go then with a bigger motor less revs and hydraulics. .
Its not as bad as that really. A couple of my friends run maximum effort v8 lumps and they reckon to freshen them up at around 50 hours. That is 50 hours of flat out driving, the 3k road mileage you do would have no impact on the engine life whatsoever. Most of the time it`s just for inspection of parts and re assembly, gaskets, rings and shells. Not a great expense and good insurance. On another subject touched on here is opening of the oil filters and checking for debris. On the last silly hp chevy engine i built I used one of those oberg tell tale filters with a removable screen , they also have a switch that activates a light on the dash as soon as there is any rubbish on the screen.


I cant find a picture of the inside of the oberg but this one is similar.




Bob
 
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