How to build the best 8000 rpm Ford small block

[Alan P.]

I know there is a lot of talent on this site and was hoping to get some advise. I want to build a 8000 RPM motor for road racing that can run on pump gas and still make 425+hp. I want to do this and stay at or under 331 cu in. Ideally closer to the old Trans-Am 302 format. The motor will be fuel injected, and have a dry sump oil system. The motor will see both sprint and endurance races. I don't mind giving up torque if I have to based on cam selection but the 8000rpm and hp are most important. Can this be done with out killing my wallet ?

[LENSJADE]

Why Do You Want 8000 Rpm ????????????? You Need To Run Roller Cam Plus Need Good Rods Stud Girdle Very Costly At 8000 Rpm Longevity Will Be Short

[Alan P.]

The rev limiter would come on at 8000rpm and I'm sure the peak power would hit between 7000-7500. The ability to have 500rpm in reserve would mean fewer shifts per lap and fewer gear ratios to change when going from say Sebring to VIR.

[Rick Parker]

................No

[Jac Mac]

Yes it can be done, just depends on what it takes to kill your wallet!

PM me if you dont want others to know what your 'pain' threshold is!

[LoBelly]

Since we (mostly) build replicas here then maybe look at a modern day interpretation of a Boss 302.

You can get the block from Ford Racing and I notice that CHI is making a manifolds for their 3V clevo heads to fit 8.2in motors.

http://www.chiheads.com/ (-just incase)

Lots of quality parts are readily available to cope with your 8000rpm - the hardest part is going to be finding someone with enough experience to know how to make it last at that level and that you trust to put it together. (and the $$)

I dont think you'll have to worry about the HP

Good luck & Let us know how you go with your project.

LoBelly

[blykins]

425hp isn't much for a high revving SBF. I'd go with a big bore, short stroke combo, like you say, maybe a 331/347. I wouldn't trust a factory block for very long turning 7500-8000 making over 400hp. I would go with an aftermarket block if you plan on staying at WOT for periods of time.

Of course making that kind of power at that high of rpm would basically mean that the engine would be somewhat turdish on the street.

However, to get there on sort of a budget, I'd go with a set of AFR 205/225cc heads, a large solid roller camshaft, and a large single plane intake, like a Super Victor. As the others are saying, you're gonna need to spend a lot of money in the valvetrain area. Light valves, titanium retainers, locks, stud girdle, etc.

With that combination, you'll overshoot your 425hp goal by quite a bit....another reason to not use a stock block.

[Bryan Wilson]

Sounds like you need a V8 Super car engine 600hp on the 7k rev limiter all day like at Bathurst can be done big dollars though.
Cheers,
Bryan

[Alan P.]

The motor will be for track use only but run on pump gas. A TWM style velocity stack fuel injection unit will be used. I agree that a solid lifter valve train will need to be up to task and AFR heads would be a good start with a Dart block or equivalent with 4 bolt mains.From what research I've done it would appear that a 331 motor would be as large a displacement motor that I would want to go and still achieve the high RPM's.

[blykins]

You may/may not be able to run pump gas. The duration on the cam will be large enough that it may be a total pig without a high static compression ratio.

[Rickd]

Talk to Keith Craft. He's built enough of the 331 strokers to let you know what will stay together for your application. He can also give you a price for the motor HE would recommend for your application - with either a Dart or World Products block. That way you will have a good benchmark and maybe have found your builder. Good Luck. RD

[LoBelly]

Originally Posted by Alan P.

...From what research I've done it would appear that a 331 motor would be as large a displacement motor that I would want to go and still achieve the high RPM's.

firstly - ditto

secondly re: your 331 engine displacement - are you confusing stroke with displacement? Stroke is important in high revving engines because the longer the stroke the faster the piston has to travel to get from the top to the bottom - the higher the piston speed the more stress on it (the piston) when it has to change direction.

If you go to one of the after-market blocks with a 4.125 bore then a 3.25in stroke will give you a 347 (i think) whereas at 4.03in bore the engine would be a 331.

Traditionally the higher revving engines were nicely over-square (bore>stroke) and conventional (historic) theory held that having the stoke at 75% of the bore was the optimum level (like the 302).
However with the superior parts and materials today I'm not sure that that holds.

Just FYI there is guy in our club who regularly runs his 347 up to 8k (solid cam) and he also built the engine for another club member who's shift point is set at 7400rpm on his hydraulic cam windsor 302 - both are EFI running Edelbrock heads/manifold and both are regularly street driven and exhibit very sociable behaviour. I would guess premium ULP.

I'm just saying this so you know that what you're after isn't really that unusual - it's just a bit pricier.

Have you got that book on performance windsors? A bit dated now but lots of info to help you balance the pros & cons of different configurations.


LoBelly

[Cobra #42]

Alan P, Don't know where you are located but Keith is excellent in building all types of motors, but he really good on race motors. Keith is a racer and drives what he builds. I think he would also tell you that you might get a better performing road race car if you looked at the torque and not so much the revs. Don't know your background in road racing but the less time spent of shifting and the more time driving the car will get the results you want. Also don't just look at the motor, having a car that has a great suspension and being able to put a good setup on the car is very important. Invest in your brakes and your lap times will drop. Don't mean to preach but also invest in yourself, practice and work with your team to make the car go fast. If you need any help drop me a email. don@texasdrivingexperience.com See you at the track, db

[CobraEd]

There are a lot of 400hp 302s out there. With the heads and cams available for them today that is an easy number to reach.

So, I would say that if you are gonna take a small block and stroke it, . AND run it to 8,000 rpm, you could be looking at 550 hp at the crank.

But then, . . . what do I know.


.

[Alan P.]

Originally Posted by Cobra #42

Alan P, Don't know where you are located but Keith is excellent in building all types of motors, but he really good on race motors. Keith is a racer and drives what he builds. I think he would also tell you that you might get a better performing road race car if you looked at the torque and not so much the revs. Don't know your background in road racing but the less time spent of shifting and the more time driving the car will get the results you want. Also don't just look at the motor, having a car that has a great suspension and being able to put a good setup on the car is very important. Invest in your brakes and your lap times will drop. Don't mean to preach but also invest in yourself, practice and work with your team to make the car go fast. If you need any help drop me a email. don@texasdrivingexperience.com See you at the track, db

Don, I do appreciate your input, but with my experience as a BSR driving instructor over the years, I have found that fewer shifts would be better accomplished with a higher revving motor as has been done with both Ferrari Porsche and BMW. Those makes have done pretty well with that format ,high RPM , good HP, not torque.MHO.

[bobcowan]

You're not asking for much when you really think about it. This can be done with off the shelf parts. Just pick up the phone and order what you want.

The lower end is easy - Dart block and Eagle rotating assembly. Keep the stroke under 4" and you'll be fine. Displacement is king, so don't be afraid of a little more of that.

Solid roller camshaft is a must. Big rocker arms and studs. Consider a stud girdle.

You'll be moving a lot of air. So you need heads and intake to match that. Look at Dart, Brodix, Canfield. Some of the pro builders I trust do not recommend AFR.

Since you'll be using EFI, street manners should be very good. The EFI will tame that radical cam and make it purr like a kitten on the street, but scream like a tiger on the track. Make sure you port the intak manifold to allow for the additional air flow at 8,000.

Carefully consider your ignition choice. Since you have a computer for the EFI, I would also get one that manages the ignition. Then you can use a crank trigger distributerless system with a coil pack. That will be extremly accurate at high rpm's, and still give you good coil saturation. Since you'll be using a dry sump with an external pump, you'll take all the strain off the camshaft. That's a good thing.

Collecting all these parts is pretty easy. Like I said, just pick up the phone. Assembling them is another matter. It will require a very meticulous attention to every last detail. If you're up to the task, great. If not, call a pro like Gordon Levy or Mike Forte.

[Alan P.]

Bob, thats good information. Your choice for heads is what I need to hear as I had taken for granted that AFR was the head of choice for this project.

[Doug I]

Spinning a mill to 8k with 425hp is easily doable. Not cheap for sure but many good engine builders will be able to deliver that.

If you want to go a little further ....... give these guys a call
http://www.coatesengine.com/index.html

With their heads on a strong bottom end you could spin it north of 10k. The fuel system would need careful design to keep up - but again any good builder will be able to do that. It would sound .... interesting.

[DAVID GAGNARD]

Alan, not that hard to do and not that expensive (cept for the fuel injection part maybe).... I built my own 331 for my 65 Mustang Coupe road racer, I shift anywhere from 6,000 to 6,500 and have a 7000 chip in the MSD box....I hit the chip on a couple of tracks (VIR for one) and have no doubt it would live with an 8,000 rpm chip in it,my cam just want support that high rpms......three years now on track, freshened up the motor after 50+ hours of run time. My engine made 472 hp and 442 torque on the dyno, but it is not a pump gas motor, 12.5 to 1 compression.

I used a very old set of Edlebrock alum heads (3rd hand when I got them), Victor Jr. intake, Demon 650 double pumper, cam is a solid roller, 586 lift (really kinda mild) idles at 800 rpms all day....Just switched to the new BOSS 302 block (don't do it, use a Dart block), Eagle forged 4340 crank,3.25 stroke, Eagle forged 5.4 H-beam rods, Diamond domed pistons.......

Using the same combo with flat top pistons should get you a pump gas (93 octane) motor, should end up around 10 to 1 compression, add a little more camshaft and I'd guess 425+ hp would be real easy...better heads should net you another 25 to 40 hp....

You'll need to be real careful on valve springs/retainers/valves, that's where you need to use the best parts you can afford, and I would not even consider using a factory (stock) block, go with a Dart 4-bolt main block....

Another thing you might want to consider is going with the standard 302 stroke of 3 inches and the big bore 4.125 bock, Dart has them also, for your high rpm application....

My motor makes really good torque down low, so I rarely use 2cd gear on track, 3rd and 4th 95% of the time.....

David

[bobcowan]

Originally Posted by Alan P.

Bob, thats good information. Your choice for heads is what I need to hear as I had taken for granted that AFR was the head of choice for this project.

On the net, AFR's are very popular. Lots of people think they're the bees knees. I'v never used them, so I can't say from personal experiance whether they make power or not.

But two pro builders that I trust tell me they would not use them. The casting and design are pretty good. But the valves, springs, and studs are not good. By the time you upgrade all that stuff, you've spent too much money.

I'm using stock out of the box Dart 195 heads on my Dart 427W. All I did was port match them to the intake. It makes 470 on the chassis dyno. Plenty of flow there for a 347.

Gordon Levy is building me a custom set of CNC Brodix heads. With his cam, we expect to be in the 620-650hp range.