Help with engine choice.

[Russ Noble]

Simon, have another look at Fran's preference.

A nice drivable smooth Weber 427. If you want "pub currency" then just inflate the figures to 600/600! That'd be quite believable for a Webered 427.

The bits that give that sort of power and torque are inside the motor and can't be seen.Then you'd have the best of both worlds, a really tractable car ("it's the Webers, you know") and impress the wally wankers with the bogus 600/600 wow factor. QED

Cheers

 

[Paul Thompson 'Hooligan']

Hi Simon

Great thread this, lots of interesting opinion/input.

For my part - I've driven a number of 40s and not a lot sounded better than Roys 302 4bolt on Kinsler injection and solid roller lifters at 8K... it didn't have a huge amount below 3500rpm but all hell broke loose at 6K and it just went on and on....

His alloy 347 was a different beast indeed. based on a 302 with .125 overbore and .25 stroke, it had serious amounts of grunt from as little as 2000 rpm... Was great for sprints and hillclimbs, great off the line (esp in 2nd) and would pull cleanly from the tightest of hairpins... to be honest it was a better 'all round' motor than the 302 and still fun on the road.

It REALLY does depend upon what you're intending to do with the car.

'Bragging rights'?? - well 350HP can get you in a heap of trouble if you're careless, so god help someone not concentrating if they've got 500+ !

The best bragging rights would surely come from being a good 350HP driver that manages to stay ahead of a 500HP driver....

Still, whilst we're on the subject, a few pics of the motor going into Bjorn's GTD for 2008.... alloy, injected, based on a 351, 427ci and 572BHP...

 

[Howard Jones]

You need to really, really think about the gas you will use. You CANNOT run that SB 600HP engine on 91 octain pump gas and have it put out 600HP. Even if you tune it for race gas at the track and pumpgas on the street, how much hassel is that worth to you.

On the 600HP SB. Make sure you understand the life expectancy of the valve train in that motor. I bet if you ask the builder about this he will steer you towards a different motor for a street car.

You really do not need a race motor in a track car. Think ballance. This type of track driving is better suited to a big inch motor, 400+ inches, and a pumpgas tune. The 427 (351 based) with a hyd roller cam, 750 Holley, and about 10 to 1 CR will make an easy 400+ HP, maybe 450. The engine will last several years and you can simply get in it on a Sunday morning and drive anywhere you want. Fill her up anywhere and drive home.

Last time out at a open track day I was on the track with a 600HP + Corbra, a brand new Mustang Shelby 500 (550HP), and a couple of 7000+RPM SB track only mustangs on slicks.

I was able to run them all down in less than 15 laps (30 min). I have really, really good brakes, a Quaife diff, decent tires (Sumotomos) sp? and about 300hp at the wheels. The Shelby put it into the wall, the corbra had it so sideways he pulled off the track, and one of the mustangs came up to me afterwards and wanted to know why my car was so much quicker on a lap when he could see that he had more power. He said "you were going in so deep on the brakes I let up to keep from being in the big one only to watch you run away from me corner after corner". Remember he was on Hoosiers.

By the way the one car that was a handfull was a Mini on slicks, gutted out interior with a full cage, and a big supercharger. I was right at my personal comfort level in the center of the corners and he could pull me off the corners until I could get full power on. That thing had a hell of a set of brakes on it too. I think maybe I was about a 1 sec to 2 a lap faster (2 min 17 sec lap) than he was but I also think I was trying a lot harder. He had about 230-250 hp I would guess.

So do what turns you on, but I bet you take out that 600Hp buss bomb after a while and put in the big inch motor. If you have the money for a 8000 RPM SB you can afford a Aluminum 351 (427) BB. Best of both worlds!!! Good power and light weight. Ballance again!
Go with the lazy reving big inch motor, after all, that's what Ford did......remember.

It's all about the ballance baby!

 

[Simon Rider]

Karl,
i've had a word with Lloyd at T & L who took the time to go over the engines and options. He uses new Dart blocks for his builds, when i asked if he could source a seasoned block the reply was pretty much a flat 'no'. Apparently he'd done this before for a customer and it turned out to be a royal PIA. The older blocks are now getting in short supply and the 1st few he found had various faults which made them unworkable. However there are, ahem, other ways around this issue i've since found out.
As for my choice of engine, the jury's still out. As you've read the general consensus is the 600 hp option is just too much as is the 500 in all honesty, but that will probably have a more usable torque curve. I've asked Lloyd if he can send me dyno charts of these engines to see where the power is being made. Will keep you informed.

Simon.

 

[Simon Rider]

Thanks for all your quality input lads, it's all slowly sinking in.
Paul, with you on the sound of a high rpm mill with solid lifters. Regardless if what i go for in the end i'd like it to have these and i feel more than upto the job of setting the valve lash every so often, relishing the thought in fact !. Not sure about the 3500rpm wake up point of the 1st motor you mention, but then again i've owned sports bikes that don't really do much until 7.5-8000 rpm and quite enjoy the spirted use of the gears to keep the tach in the sweet spot. Lovely looking engine by the way, with a lovely price tag no doubt being one of Jacks efforts

Howard - here in the uk normal pump gas is a bit tastier @ 95 ron with 99 ron widely available. The advert for the engine actually states that it's designed for 'extreme' pump gas. I did have a chat with Lloyd about these engines and asked for his honest opinon as to what real life with these engines would be like. You may be surprised that he pointed me straight to the 370, saying that the webered 427 was what he called a 'show' engine and that the carbs were in fact holding the engine back. He seems very proud of the 370 saying it's 'a big engine in a little skin' that will give me plenty of reliable service with a normal maintenance regime. But is he being wholy objective...

With the £-$ rate being what it is, i'll be going for the ally block option regardless.

As i mentioned in the post above i'm (hopefully) going to get to see the dyno charts for these animals. If it's ok with Lloyd i'll post them here and you can see for yourselves.


Simon.

ps- You've probably all seen this before, but oh to get an engine that sounds like this one !
YouTube - Gt40 losses control

 

[Jac Mac]

If his '370' is based on 8.2" block with 4.155 bore & 3.4" stroke then I would pass & opt for the 3.25" stroke with same block & bore for around 350 cu in. Rod ratio is more friendly & RPM capability higher seeing that your want a solid cam etc.

Jac Mac

 

[tom pritchett]

Bill has it right. I have a 351w b&s to 427 with 48 ida's, a huge cam, and custom heads. this gives me about 700 hp. I have been at th track 3 times and broke the car 3 times. If you really want to drive the car, go with a little less power for the reliability aspect. I broke the outboard cv, ring and pinion in the zf, and now, blew out the bead gasket in #3 hole. I love my car, but would love to spend more time driving it. The more something is tweaked, the more tempermental it is. my 2c! good luck. tom

 

[Russ Noble]

Hmmmm...... The 48's don't seem to be holding Toms engine back........

Wot's wrong with a "show" engine anyway? It's going to be the most drivable of the lot and should still be able to light up the tires without much provocation. How much road going tractability do you want to sacrifice for a big rev track day screamer.

 

[Simon Rider]

Russ, absolutely nothing wrong with the 'show' engine at all - it looks fantastic with those carbs and at 500hp is hardly 'all show and no go'. Lloyds view of webers is an understandable one comming from his world where it's all about getting the max output for a competitive price.

 

[Ron Earp]

Howard - here in the uk normal pump gas is a bit tastier @ 95 ron with 99 ron widely available. The advert for the engine actually states that it's designed for 'extreme' pump gas.

The method of rating octane differs from the UK and US. There is a thread about this on the forum that we had some time ago:

Pump Gas Octane

http://www.gt40s.com/forum/gt40-tec...-octane-no-s-usa-uk.html?highlight=RON+octane

Basically, the 93 pump octane in the US is equal to the UK 98/99 octane gas.

Ron

 

[Simon Rider]

Thanks Ron, what's considered 'extreme' pump fuel then ?

 

[Ron Earp]

That question is sort of like what is a Stage III head prep? Means different things to different people.

'Extreme pump gas' I think is a term for "out of the ordinary pump gas". Near a couple of the drag strips here in North Carolina the normal automobile gas stations carry 100 Octane (US rating, so about 105 or 106 for you guys) gas. Clearly, they carry it due to need and demand.

Our local road course, VIR, has 100 and 110, both out of the pump but naturally that is at a race track.

I don't think I'd want to build an engine that required higher than 93 octane (98/99 for you). Availability of the gas is limited. Of course, you could have a timing retard setup to run the "normal pump gas" and another setting for the "extreme pump gas".

Ron

 

[Simon Rider]

Thanks. Well i guess that's taken the 370 out of the equation. To echo what Howard put in his post, it'd be just too much hastle. I was moving away from this option anyway. I'm a little concerned that Lloyd didn't bring this to my attention as a potential concern when i asked about having to live with these engines - of course 'extreme' to him could mean 98/99 ron.

 

[Howard Jones]

93 octain would be quite an improvement over the crap we have here in California. 91 with 10% alcohol. I still wouldn't go much beyond 10 to 1 compression (with cam timing taken into account). Believe me 500hp is plenty! I think you should take a ride in a 500hp 2500 pound car around a track before you put that much power into your car. I think you would be surprised just how little of a lap the peddle is on the floor. On the street it won't matter, it will all go up in smoke under a 100MPH anyway.

In defence of big power at open track events, Sometimes (read often) the big power guy just blasts off down the straight and since most of the turns, if not all, are out of bounds for passing the only way by is to wait until he get flagged out of your way. This can be frustrating but it can be solved with enough power. Just don't forget the big brakes to go with it, 500 hp drag races down the front straight will require them.

Either way with that kind of power you will need a set of track wheels/tires (slicks). Ain't no way you are gonna like 500hp going through BFG Comp TA's or their equivalent street tire. A lot of the big block/hp cobra guys run them because of the 15 inch wheel issue and believe me it ain't pretty!

 

[Simon Rider]

Hi Howard, can you expand on the wheels/tires issue. Are you suggesting i get 17" rims to accomodate a wider choice of rubber ?

 

[Doug S.]

Simon, I'm just wondering---since you know you'll be satisfied with 500 horsepower, how about finding out if T & L offers an 8.2" SBF with a bit less of a mondo build. It's just IMHO, but I sure think the lower weight of the smaller block SBF would be beneficial to handling due to the lower overall vehicle weight and better weight distribution.

Even if you go with a less mondo build, the 8.2" 302 block is capable of achieving some pretty fine horsepower levels, and you'd still have that great solid lifter sound coming at you from behind your head! Combine that with the better handling resulting from a lighter overall weight and better F:R distribution, and it ought to be a killer combo! You could probably even get one that will run on pump fuel!! If you just MUST have webers, there are plenty of options for the 8.2" SBF, too!

Just a thought........

Doug

 

[Simon Rider]

Hi Doug,

They do other 302 (8.2" ?) block options:

eBay Store - T L Engine Development: 302: 302 DART 370 Ford Stroker Crate Engine by NASCAR Shop


i'm going to go for the ally block option thanks to the very good exchange rate. The 427 with this block weighs in at 375 lbs.

I've since learned that the 370 will run happily on pump fuel over here. Isn't there a case for the more proressive torque delivery of this type of engine over the huge gobs of it delivered from tickover onwards of the bigger displacement motors ?

I'm going to have to make my mind up soon or else my kit'll be ready with no mill at this rate.

 

[Gary Kadrmas]

Simon,

Your selection of an alloy block for weight savings is a great way to go.

The comments made by various forum members have touched on all the important factors of an engine choice for you.

The majority have stated that speed cost money, and along with that, the cost factor of how the higher HP figure relates to other components are linked to the HP.

For me, having a GT40 that performs well means having about 370-400 HP. The alloy block helps overall weight and performance. Brakes would be as important as the selection of the engine. But one thing that was not mentioned was the tire size.....which means maybe a Gulf front and rear section to allow wider rims/tires. Big HP and big brakes do absolutely no good unless you can get it to the ground. If the focus is on overall weight, having big brakes and the ability to harness your HP to the ground can only be limited by the drivers ability to drive the car to the capabilities of the vehicle. If you go with a lower HP engine, your cost for mainteneance will be lower, and the intervals of how often you have to tune your engine will be farther apart,......which means you can DRIVE your car more often.

Later on, after you have developed your skill at driving your GT40 at speed, and you find a need to have more horsepower, you can always sell your engine to another forum member, and update your GT40 to a higher HP engine.

Just my 2 cents worth.

 

[Simon Rider]

Thanks Gary, you're right - i've had all the options put forward so now it's up to me.
Thanks to everyone who's contributed. I'll let you know what the outcome is.

 

[John_1949]

How about none of the above. The best current PUSH ROD engine to run is a LS7 chevy moter. Will fit nicely in any of Frans cars. Will put out 550 HP stock, no over heating, 28 mpg, low admissions and idle at 650 rpm. If you want more HP you can put in a cam and make it 650 or if you want just insane HP twin turbos will do over 1000. I know it doesn't follow the product line but it does make a great combo

John