I think Dennis is now running a 302. Required by vintage rules. There's no doubt that a 351/427 will make more torque (lots more) and more HP at lower rpm. On the straight and exiting corners that's likely to be an advantage even in this old design. In that regard I don't think a 302 is better on the track. A similarly powered 351 will be more tractable on the street for sure. Of course, if I wanted a docile demon I'd get a Bentley. Still, I like the period correctness and the high revving madness of a well-built 302 that revs to 7.5k. Also, I'm sure I'd kill myself with more power than what a 302 can make.
SPF #2285 Born, But Still Coming To Life
- Thread starter soulcoaxer
- Start date
Yeah 550 hp in a 2300lbs car with no nannies can result in a mishap pretty quickly on track. Frankly 200hp in a 1950lbs lotus can be pretty scary if you carry the momentum as one should.
But then so many GT40s seem to have survived that I assume the design hs a degree of predictability to it.
Torque and Hp at lower rpm can be overcome with gearing.
In any event no historic racingin a Mk1 unless an iron 302 and carbed.
But then so many GT40s seem to have survived that I assume the design hs a degree of predictability to it.
Torque and Hp at lower rpm can be overcome with gearing.
In any event no historic racingin a Mk1 unless an iron 302 and carbed.
Mike
Lifetime Supporter
What sanctioning body has that rule?
I am saying the weight advantage of a 302 has its own virtues, and that there can be such a thing as too much power.
Having to work for your speed has its own entertainment. A few years ago a 351/427 may well have been faster on track and certainly even today would be less stressed and more reliable.
In the last year head tech has had major advances bringing 302 power up to 351 levels, smaller valves for low down power with flows previously seen only on a 225 head. And yes you need solid rollers to get the revs to have the power a less stressed 351/427 will put out with hydralics.
Also most motors I hear about have eagle or scat rotating assemblies which are strong, but you can go stronger and much lighter with some $$$, making for a really snappy revy motor.
Now you could do all the same in terms of heads and solids cam etc on a 351/427 and get 650Hp and 600ftlbs of torque on pump gas, maybe even more. At a certain point on track you will exceed any realitic ability of the brakes, go so fast that aero insbility is an issue and be unable to stop, and from what I hear start breaking transmission pices and halfshafts.
If I did not have an eye to vintage racing then my motor would be an aluminum block too saving another 90lbs. To me lightness is next to godlyness.
The Oltroff cars now run 302's a function of sanctioning body requirements, kinda like the 60's when the Mk2s which won lemans got outlawed and we went back to the "slower" 5.0 winning more races.. Dennis also told me that for driveline longevity on track a 302 is better, I think his race 302's are putting out north of 700hp, and with car development his lap times are dropping compared to his 427 days..
Since a GT40 cant perform like a modern track car, I guess its all about where you want to put the emphasis, and $$ to get there, a strong relaible 302 is going to cost a lot more for each Hp over 500 than a 351/427. On top of normal build costs, I am putting the money that most spend of an 8 stack plus into further upgrading internal componants to have very strong reliable power from a 8.2 deck block.
The 302 will be faster than I am a driver on track, and its vintage racing eligable.
These are recreations and we each do our own interpretation, some go for period paint schmes but have efi and 427 motors in LHD which is pretty cool and probably a much btter spec for a primary street car.
I like the idea of emphasising that hi rev sound historic type motor light wieght etc. It seems like an idea to be able to vintage race at some point.
The track issue is for me key. In the NE we have great winding roads for fun little cars like a lotus. Realisticaly up here there are no open big roads to realy run, and I have other cars that are already overkill for the street. To me these days a fast car must be track capable. I like to really use the machine all out and dont want to worry about civillians and cops, so its to the track. But my car will still be streetable(just) for those vintage rallies in Texas and Montana one day.
In the shorter term we will see if a track focused GT40 can hang with new vettes and GT3's on track which is the immediate goal.
Even the power available from a 302 sounds scary and humbling to me in a track context.
Anyway sorry for hijacking another thread.
Will correct the sponsor thing.
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I think you should discuss with Dennis, I only go by what I am told and am not a spokesman for others. But from what I am told the two most likely sanctioning bodies in the NE will want an Iron 302 and carb.
From what I hear and see there are anumber of cars built to this race 302 spec, and a few motors in production.(sperate builder to mine) These race cars have 13.1 compression ratios a very narrow powerband between 7k and 8.5 k rpm and in excess of 700hp. That makes for a very fast car on track, but is not the type of motor you would want to try for a street driven car. Nor is it the spec I am going for which will be 450ftlbs and 550 hp spread ebtween 4900RPM Tq and 7000RPM peak Hp.
If I did just what I wanted or origionaly though it would be a aluminum 302 with 8 stack, maybe getting to 500hp. But I have been convinced of the wisdom of going historc capable, and when I thought about the aluminum block I realised that loosing that much weight means altering "known" GT40 dynamics and figuring out springs shocks etc, and I dont want to be a development engineer and reinvent the wheel.
My personal opinion is that if its about historic racing somwhere a line has to be drawn, I am good with Iron 302 carb and proper Gt40 tub as spf is. Some other santioning bodies want a 289 and other stuff, which would negate a SPF.
There are a number of replicas which look like P4 ferraris or GT40's but are completly different cars underneath. Maybe there will be a series where anything that looks like a GT40 Baily, CAV RCR can run, and in which any motor will be allowed, SPF cars with their older suspension designs and brakes may not fare so well.
I am all for recreations and recreations historic racing, what is needed is a set of stadards which to me are near period standard. In fact I think recreations wills ave historic racing and fill out the fleets with cars being driven in anger while period builds can be preserved in meusuems. But without standards we will end up with car thta just look like historic cars but are otherwise completly different.
Dont have any idea who Paul is.
Anyway, you dont race/track yours so the hydralic 427 is probably the better choice.
As stated previously a 302 at 550 hp on track is overkill and well beyond the ability of most to seriously use. The english and ozzies who do track/race theirs seem to think even 475 hp is plenty, and if its all wrong, in a few years maybe I will put a 427 in or a 700hp race 302 or whatever is the flavor of the month then.
For what it costs to service and redo a ferrari motor you can change a SPF motor every few years.
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Seems the rule is must be carb, no definition as to what type of carb, I would argue that a Inglese 8 stack is more visualy authentic and slower, but rules are rules.
As to block, a 302 is an evolution of a 289 but not a 289. A modern 302 can be bored quite a bit so strictly not authentic but in the spriit of autheticity. Once again a line has to be drawn somewhere and here it seems there is an iron 8.2 deck heigh SBF, but aluminum heads Ok.
As to MK2 from what I understand a 351/427 was Ok, which as you point out has nothing to do wth an FE other than aping displacement.
I think the rules get expanded and restricted based on grid size and applicants, but there seem to be certain hard limits..
Following this thread with interest but I am a bit puzzled about these sanctioning body rules which mandate an iron 302 on carbs but allow mods to get "north of 700hp" Firstly, that would be some trick 302 with that kind of power, or at very least the heads will be in NASCAR territory and 8k rpms the norm which kind of defeats the object of restricting modifications to a more historic entity.
The way they do it in (European) FIA Post Historic is to strictly control the components so as to achieve some kind of historical parity (not the Historic Passport). There is no way on God's earth, applying the FIA rules, you would get anything more than 325hp out of a 289 Mustang for example and even then you would be pushing it.
I wonder even if a GT40 type chassis with authentic & historical type suspension and brakes could even USE 700hp?
Sorry for any drift but just curious.
The way they do it in (European) FIA Post Historic is to strictly control the components so as to achieve some kind of historical parity (not the Historic Passport). There is no way on God's earth, applying the FIA rules, you would get anything more than 325hp out of a 289 Mustang for example and even then you would be pushing it.
I wonder even if a GT40 type chassis with authentic & historical type suspension and brakes could even USE 700hp?
Sorry for any drift but just curious.
Jack Houpe
GT40s Supporter
A 302 making a 700HP would have to have forced induction or maybe it spins to 9000 RPM, either way I don' think it would be reliable. Just to think I was looking to swap to a 331 to drop a couple hundred HP, dang I guess I would be going the wrong way. :laugh:
I am going to hazzard to guess that allowing some more modern componants on a 302 block contains costs. BTW a 302 is not justa 302 a boss or dart 302 wighs a bit more, is a lot stronger and can comfortably be bores 4.125, so you really have a 331.
From what i read a 289 block will break apart north of 400hp and a "normal" 302 block splits down the middle when you go ver 500hp.
The old Gt40s seem to be confortably pushing past 500hp and on to 600. One is even rumpored to be runnign acustom flat plane crank. Maybe they have 289 blocks but these are new build and internaly strenmghthened to a huge extent.
As to whether aGT40 can handle 700 hp, I suppose more Hp is a law of deminishing returns, and making thta power in a very narrow band probaby does not overwhelm esp as modern "period" race tires are so much better. But yeah it takes nascar heads, titanium valves etc.
Now 650 or 700hp with tons of torque everywhere as from a 351/427 may well overwhelm, it will certainly from what multiple people have told me, lead to premature drivetrain failure on track. Most 351/427's seem to be in the low 500-550hp range with hydralics. Really an understressed not too expesive to build motor that is relaible and durable with instant go from low revs, ideal for the street. But however you look at it modern methods bring more power from same face spec.
Look at Cobra clones. An orgional 427 was actualy a 428 with 325 hp(as measured in the 60s, and the few Sc cobras were 427 sideoilers of not more than 475hp. The 427 was Nascar motor, short stroke big bore designed to live at sustained revs.
Nowadays you can get an aluminm FE 427 style motor with 428 style crank of 540 CI and 675 hp. It will chug along with a mountain of torque at low revs. Not sure how you drive it up the power band, but the power is there. Even if you go 427 iron block Fe with 427 crank and hydraulics you are well into the mid 550's with pump gas,
One day when I build a cobra it will be a 427 block and crank, these were hi rev Big blocks and cosiddered somewhat or "relatively" soft down low compared to the 428. Not having driven acobra in a while, I think the last thing they need is more torque, but being able to rev and have strong power everywhere is in keeping with the 427 concept. Frankly a 351/427 is going to outperform a 60's fe 427, at least as long as it stays together.
Now back to GT40s. Even a moderate build 302 is going to put out 475 hp with todays heads. Which is 50 more than the best did in the 60s on race gas. But like the 60's cars a 302 will be more of a revy motor.
Modern tech and build, precision, head porting piston design etc means any vintage motor from a Jag SS to healey is going to be more powerful relaible and smooth. The trick to me is keeping the nature or essence of the machine as it was.
A modernised high rev 302 is sort of like the 60's cars, and given that we dont change/optimise gearing for each track, probably on average performs the same.(lemans cars were geared to go 200 for shorter tracks GT40s were lucky to have gearing for 160), now one motor and set of gears covers the range on normal fuel.
Those period Gt40s racing at goodwood, they were all reputedly north of 600 hp.
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Mike
Lifetime Supporter
Why would that not also be ideal for the track? There's not much difference between my engine and what Dennis races with. He doesn't scream it around the track. Very smooth would be a better description. I'm struggling to follow your reasoning why a 302 is a better track setup.
[ame=http://www.youtube.com/watch?v=usQtCnZEBlE]Olthoff Racing at Virginia International Raceway October 2011 - YouTube[/ame]
You could go for a 3.0 stroke 4.125 bore 302 for a 331, a 3.25 crank 4.125 bore 302 for a still short stroke 347. Or a 3.4 stroke 347, or the 3.4 stroke and 4.125 bore and have a 363 which will be north of 500hp on hydraulics and pump gas, but then you might as well have a 351/427. If you want smooth revs its about rod ratios, which means to me not more than a 2.25 crank with not less than 5.4 rods on a 302.
A rousch or ford mtorsports crate with the above specs is going to be 500 hp (363CI) or less on hydralics, a crate 331 with 13.1 is going to also be 500hp with eagle or scat internals and solids. I have heard of 363's with solids going to 625hp.
But to do the high rev smooth running 302 right imho you need to understand the pieces, get the premium optimum bits, have the best heads cam etc, everythign made to your spec for your mtor spec, have the motor custom built, and then yeah 550hp and 450 ftlbs is possible over a broad range, in any event I am going to find out the result real soon.
Think about it, many NA street cars produce over 100hp per liter, some even 120, its a function of head design and valvetrain that can handle the necessary revs. The pushrod and single cam are the two biggest limiting factors and you can work around those if you are prepared to set valve lash every 2k miles. Cranks pistons and conrods, they can be light and strong for 10k revs, just a function of some $$$.
As to the 700hp motors. From what I hear they are NA, 13.1 comprssion make peak hp at 8500rpm have a very very narrow powerband and are weak below 6k rpm, and have about 35k in parts alone to stay togethr at those revs on road track. They also apaprently last few seasons.
Heads make power, that and cams, the rest is strength. Between computer modeling and cnc machining the new pushrod motors really can make power. The weakness is always the pushrod vavetrain, it just cant be as robust at revs as an ohc motor, and to get a lot of power froma 302 you need revs, but you can work around the valvetrain drawbacks and deal with soild roller, shaft rockers maintanace etc to get close.
Now wind down the spec, go for the bore all the good bits and great great heads, and 11.1 compression ratio(which is borderline for the street or a bit much) solids so it can spin and low to mid 500's is possible with really nice torque and a great spread of power. No it wont spin the tires at 3k rpm in second gear like a 351 427 will. The power is at its peak from 5k up. Its all a function of what you want and what power charateristcs are important to you and the type of driving you do.
For me amongst other things I may not want to have to shift from say 3rd to 4th at 6250 rpm on a sweeping bend, maybe it suits to just lets the revs run into the high 7s as you are not using all the power anyway and a shift on a corner will waste time and upset everything. Or soemtimes you are almost at the end of a straight but running out of revs. In other words reavbility and a broad reach has its own advatages. Think vette vs ferrari. Same track performance more or less, just different way of getting there. Lower torque at lower revs, say comming out of a bend, I think my motor will be strong enough by 4k that one will be more concerned with spinning the car than not enough power.
Plus its a whole lot of fun to figure out your own motor, learn the SBF bible and see what you come up with, just like building the whole car.
The hard part for me now is figuring gear ratios.
Weight(helps brakes and tires), as well a and where the weight sits(better cornering) , being able to hold gear longer, sanctioning body requirements. On the subjective its sound and feel from the revs. Subjective and objective is you have a snappy motor.
Its not just how fast you go, but also how you go fast.
Dennis said that you can bore to 306, iron block, solid lifters to be historically eligible. On race gas they're pushing 550 gross HP. I don't think you can get 600hp out of a carb 306 unless you force the induction.
For FIA you need a number of suspension and brake modifications.
Per Dennis, you have to set one up for pre-64 (I think) or the GT40 is not competitive in historic racing.
Best,
Ron
For FIA you need a number of suspension and brake modifications.
Per Dennis, you have to set one up for pre-64 (I think) or the GT40 is not competitive in historic racing.
Best,
Ron
On a slightly different note, does anyone know the specs (cam lift, duration, lobe) on the original cars?
Sorry again for thread interruption/drift but looked up SVRA and the GT40 make is greyed out so not eligible I guess but this is what they have to say:
"
Rules & Regulations
These rules are general in nature and may not apply to every car accepted by SVRA. It is not possible for SVRA to publish rules that accurately define the period authenticity for all eligible cars.
It is therefore the responsibility of each competitor to research the proper period specification for his car, and to present it as such. Supplemental Regulations (Spec Sheet) are published for most Makes & Models and they give specific details on permitted options and modifications. The (Spec Sheet) are to be used in conjunction with the General Rules and Regulations (GRR). When in conflict the (Spec Sheet) takes precedence. The Group Supplemental Regulations (GSR) for each Race Group contains details that apply to that group only and these should also be considered when preparing a car.
Proof of any unusual specification or configuration is the responsibility of the competitor. Updating or backdating within a recognized model (body type) production span is allowed as long as it does not conflict with the group eligibility time period. Continuation cars may be accepted, but they must be backdated to the eligibility period. (my underline)
These are the resources and regulations that will help you prepare your car to compete with the SVRA:"
I think that safely rules out any 700 hp 302's (even it it were practical/possible)
"
Rules & Regulations
These rules are general in nature and may not apply to every car accepted by SVRA. It is not possible for SVRA to publish rules that accurately define the period authenticity for all eligible cars.
It is therefore the responsibility of each competitor to research the proper period specification for his car, and to present it as such. Supplemental Regulations (Spec Sheet) are published for most Makes & Models and they give specific details on permitted options and modifications. The (Spec Sheet) are to be used in conjunction with the General Rules and Regulations (GRR). When in conflict the (Spec Sheet) takes precedence. The Group Supplemental Regulations (GSR) for each Race Group contains details that apply to that group only and these should also be considered when preparing a car.
Proof of any unusual specification or configuration is the responsibility of the competitor. Updating or backdating within a recognized model (body type) production span is allowed as long as it does not conflict with the group eligibility time period. Continuation cars may be accepted, but they must be backdated to the eligibility period. (my underline)
These are the resources and regulations that will help you prepare your car to compete with the SVRA:"
I think that safely rules out any 700 hp 302's (even it it were practical/possible)
306 is the safe bore limit for a stock 302 block. You can run a Boss ford block or a Dart block in whch case you can safetly bore to 331.
In any event what is and is not allowed is all a function of how many cars they can attract vs spec, and how the car performs compared to others. Lets not forget Dennis used to run a 351/427, and his winning ways with that setup brought in the 302 rule.
The real debate is centering around allowing visual representations which are modern cars like a Baily or RCR. There are already some t70s running from gtd which are not lola cars at all. So I am good with drawing the line at a SPF which is a "proper" GT40 tub and suspension layout, with Iron 302.
I know about the FIA limits, for that really you need a gelescoe car or a lot of mods to a spf.
Currently most period Gt40s will not run local series so recreations come to the fore, and crowds love these big bruisers. From what we know a 302 is already not a 289. Its just a function of where the line is drawn and from what I understand its an iron 302 with carbs, proper Gt40 type tub. Brakes yeah if you go 64 spec they are solids, but I will def run vented.
In my case I am not intereted in going to the nth dgere and being a front runner, or campaigning a whole season, dont have the time for one thing, its just about having fun and maybe entering a few races close by like the Glenn. From what I hear my car spec would be permissible, esp if I dont win races but help fill out the grid.
In the meanitime the plan is to get in about 15 track days over season while learnign the SPF. Joining monticello and will continue to track at other locations with the SCDA which is a great organization. Based on my lotus mileage per season should be somewhere around 3-4k miles, plenty of fun, plus the lotus is still there for small tracks and honing that momentum art.
The other part of the plan is to spend a few days with Dennis at a track once the car is done, learnign from the master.
From what I see Dennis would blow away most of us with a 425 hp 302 while we had 600hp, so there is a big learning curve before worrying about power.
