Jack Houpe
GT40s Supporter
Yes sir, but it still would have a crazy torque curve.
Cam change
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Yes sir, but it still would have a crazy torque curve.
450HP it will still be a weapon Jack.
One thing you may want to consider is the throttle linkage ratio, it will make it easier to control if you have a longer throw on the pedal.
I put as much as I could in mine as it makes it easier to drive in traffic.
Throttle bodies are very sensitive.
I see threads with claimed 600hp plus, all I think is yip that will be interesting to drive.
I know of another owner who upgraded from 350 to 550 and he has told me it ruined the car.
Jim
One thing you may want to consider is the throttle linkage ratio, it will make it easier to control if you have a longer throw on the pedal.
I put as much as I could in mine as it makes it easier to drive in traffic.
Throttle bodies are very sensitive.
I see threads with claimed 600hp plus, all I think is yip that will be interesting to drive.
I know of another owner who upgraded from 350 to 550 and he has told me it ruined the car.
Jim
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Jack Houpe
GT40s Supporter
Mike Trusty suggested years ago a cam type linkage, when I get the intake off I'll investigate that option Jim but really would like drive by wire as then you can add traction and cruise control. 
I bought a GM unit to experiment with.
Sent all the information to Crane Cams yesterday, lets see what they have to say. I wish Jack Mac would chime in.
I bought a GM unit to experiment with. Sent all the information to Crane Cams yesterday, lets see what they have to say. I wish Jack Mac would chime in.
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Jack Houpe
GT40s Supporter
Ok spoke with COMP CAM not crane cam sorry for the typo. Heres the news, not good. There is no smaller cam that will bring torque down, in fact they said it would increase the torque and it would come on sooner if I went with hydraulic lifters and a lower profile, (this is confusing to me???) in fact he said to decrease torque I should go with more over lap but it will not help much. I told him I wanted to drop torque 150 ft lbs. He said to decrease torque that much I will need to change compression ratio or displacement or both. So those of you who chimed in about changing internals you where right. I'm still thinking what to do. Don't shoot the messenger please.
Jack Houpe
GT40s Supporter
Jack Houpe
GT40s Supporter
Jack,
I read through all the posts in your thread and before I got to Jim Cowden's my suggestion was going to be the same:
1. Before you do anything else, change the throttle linkage ratio so that the throttle has to de pressed a lot further to get to wide open. That will make the tip in much less sensitive. This is probably the lowest cost mechanical improvement that you can make.
2. As others have basically said, the throttle should be treated like a rheostat and not just an on-off switch. This will be a lot easier if the linkage is modified to require a lot longer throttle pedal movement.
3. As Jackie Stewart once said, press the throttle like you have an egg under your foot. Don't mash the throttle.
4. When on track remember one of the golden rules about corner exit and throttle application - imagine that you have a rope between your upper hand on the steering wheel in mid corner and your throttle foot. As you unwind the steering wheel you can depress the throttle more. Be smooth!
5. As others have said, changing the cam to a milder cam will probably keep the same peak torque but at a lower RPM.
6. When the Weber's were on the car during the dyno pulls, the venturi size was limiting the power and it nosed over by 6,000 RPM. The TWM's probably have a 50 or 52mm bore versus a Weber Carburetor's 48mm main bore but 42 mm +/- venturi's. I would think that the cam that you have and the AFR 225 heads and TWM EFI set up are good for about 600 to 625 HP or so at between 6500 to 7000 RPM and probably close to 570 ft lb of torque at about 5000 to 5200 RPM.
Do you have a good torque sensing type differential unit?
Good luck and keep us posted on what you do!
Gord
I read through all the posts in your thread and before I got to Jim Cowden's my suggestion was going to be the same:
1. Before you do anything else, change the throttle linkage ratio so that the throttle has to de pressed a lot further to get to wide open. That will make the tip in much less sensitive. This is probably the lowest cost mechanical improvement that you can make.
2. As others have basically said, the throttle should be treated like a rheostat and not just an on-off switch. This will be a lot easier if the linkage is modified to require a lot longer throttle pedal movement.
3. As Jackie Stewart once said, press the throttle like you have an egg under your foot. Don't mash the throttle.
4. When on track remember one of the golden rules about corner exit and throttle application - imagine that you have a rope between your upper hand on the steering wheel in mid corner and your throttle foot. As you unwind the steering wheel you can depress the throttle more. Be smooth!
5. As others have said, changing the cam to a milder cam will probably keep the same peak torque but at a lower RPM.
6. When the Weber's were on the car during the dyno pulls, the venturi size was limiting the power and it nosed over by 6,000 RPM. The TWM's probably have a 50 or 52mm bore versus a Weber Carburetor's 48mm main bore but 42 mm +/- venturi's. I would think that the cam that you have and the AFR 225 heads and TWM EFI set up are good for about 600 to 625 HP or so at between 6500 to 7000 RPM and probably close to 570 ft lb of torque at about 5000 to 5200 RPM.
Do you have a good torque sensing type differential unit?
Good luck and keep us posted on what you do!
Gord
Jack Houpe
GT40s Supporter
You got me on that! Help me out a little please, what is that?
Right now I'm frustrated.
Thanks
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Jack Houpe
GT40s Supporter
Jack,
Changing out the motor sounds like a big job, but it will allow you to not only put in a smaller, lighter, cooler, quieter motor, but you can fix that pressure plate. In the end you will have a car that you can really enjoy, even at Monterey
Yes Jim you are correct, although overheating (the car) has not been a problem. The pressure plate will be one of the first things on the list.
I still say you have the hard parts for the ultimate street Gt40 motor starting with the alumnium block. By ultimate I dont mean max power. Put a shorter stroke cank in your motor and cam to go with it. Stroke is troque, shortening the stroke back to stock will give you a very smooth running motor with less torque and power futher up the rev range. It will make the whole car a lot more driveable, will be less stressed than a 302 and not too dissimilar.
An aluminum 351 motor is great, you will probably get down to 380 -400Ci. An iron 302 will weigh the same or more, and if you go alumnum 302 it starts to add up quick. A very good iron 302 with a 3,25 stroke around 500hp is going to cost you not less than 12-14K, then you still have to do induction etc. I say dont throw out what you have, just redo it for what you want.
If you decide to go 302 I have rsearched mutiple combos and builders, but if it were me I would just destroke what you have.
An aluminum 351 motor is great, you will probably get down to 380 -400Ci. An iron 302 will weigh the same or more, and if you go alumnum 302 it starts to add up quick. A very good iron 302 with a 3,25 stroke around 500hp is going to cost you not less than 12-14K, then you still have to do induction etc. I say dont throw out what you have, just redo it for what you want.
If you decide to go 302 I have rsearched mutiple combos and builders, but if it were me I would just destroke what you have.
I dont think we are spoiled for choice on engine components for the SBF. Most after market tuning parts including the stroker combos are aimed at the drag scene, they produce gobs of torque that only a drag car with massive slicks ,frigged torque converter/trans and loads of weight transfer can use. These engines are a far cry from the ideal light car massive rev range screamer that the car in track form needs. So I too am building a short stroke screamer which will take advantage of the limited gearing options and traction afforded to the build. Cammed to rev
Bob
Bob
I dont think we are spoiled for choice on engine components for the SBF. Most after market tuning parts including the stroker combos are aimed at the drag scene, they produce gobs of torque that only a drag car with massive slicks ,frigged torque converter/trans and loads of weight transfer can use. These engines are a far cry from the ideal light car massive rev range screamer that the car in track form needs. So I too am building a short stroke screamer which will take advantage of the limited gearing options and traction afforded to the build. Cammed to rev
Bob
That's my boy! :thumbsup:
Jack Houpe
GT40s Supporter
I've sent a letter to Olthoff, I take his advice seriously. 400-450 HP no more!
Going to talk to friend today about options, he has a 289 with webers in his garage that I don't see going in anything, I,m going to look at all variables.
What displacement Bob?
Sean the motor is beautiful to look at, after waiting over half a year to have it built, it arrived! A friend and I sat in the garage and had a few beers just looking at it, to me it was the Mona Lisa. :laugh:
Going to talk to friend today about options, he has a 289 with webers in his garage that I don't see going in anything, I,m going to look at all variables.
What displacement Bob?
Sean the motor is beautiful to look at, after waiting over half a year to have it built, it arrived! A friend and I sat in the garage and had a few beers just looking at it, to me it was the Mona Lisa. :laugh:
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Jack,
I was discussing your situation with Dennis yesterday (he does not often get to the boards he is so busy) and he said in his best SA accent "I tell and tell people 500 plus is TOO much!"
I have a customer with a MK I that is about 600/600 and he has admitted that perhaps bench racing got the better of him.............
The first 40 I built had a heavily worked 302 with a 310 duration solid lifter cam and itb`s . That topped 500 hp in the rollers and had a nice spread of torque all the way up to 7k+ rpm. Despite the cam the car lives on the road and is perfectly tractable which I think is down to the programmable ecu. The same cam that went into my friends Alpine Tiger was taken out the same day, with a carb and points it was un tunable, it had horrendous lope and massive flat spot off idle. The one I am putting together now is an svo block with a bryant stock stroke crank, I can grab the extra cubes in the bore without putting piston speed on another planet. I know the general consensus is the strokers will live with the high revs but from what I have seen it only applies to very short burst`s of a few seconds ( drag racing ). The circuit race cars with strokers are running internals that cost mega bucks that are binned after every race.
Bob
Bob
Jack Houpe
GT40s Supporter
Rick, in 08 we discussed this, I was frustrated as the car was new and uncontrollable for me and far to scary to drive on the street, he told be before I do anything buy avons and he was correct, the tires quit skipping at 95 MPH. In my note I asked options, he will get back with me.
Thanks Bob
If any of your are running a short block w 289-302-331 what ever and have a torque hp dyno sheet, please share here if you don't mind. It will be interesting to see what others have.
Did they not have an cosworth engine in the first car? Where the headers come from between the heads?
Thanks Bob
If any of your are running a short block w 289-302-331 what ever and have a torque hp dyno sheet, please share here if you don't mind. It will be interesting to see what others have.
Did they not have an cosworth engine in the first car? Where the headers come from between the heads?
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Ho ho! That's a Ford DOHC Indy engine you're talking about. Pure home grown US Detroit (but exotic) muscle. I think a couple ended up in 40's but they were not well enough developed for the 24hrs of Le Mans. I think GTP 103 had one but it wasn't supplied that way from the factory.
Gurney took over the program and ran that engine very successfully as the Coyote in Indycar for many years before Cosworth. I believe Bob a member on this board bought the entire stock of the Gurney Eagle Indy motor, that's if you REALLY want one at around $25,000 +
If it were me, I wouldn't hesitate but you're not going to have a nice time on anything else but a race track with it. Zero practicality.
Gurney took over the program and ran that engine very successfully as the Coyote in Indycar for many years before Cosworth. I believe Bob a member on this board bought the entire stock of the Gurney Eagle Indy motor, that's if you REALLY want one at around $25,000 +
If it were me, I wouldn't hesitate but you're not going to have a nice time on anything else but a race track with it. Zero practicality.
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