Tracking a SPF

B

Sean

Igofaster said:
Sean,

Depending on where I look, I get block weight diff between 302 and 351 at 25-45 lbs, all up motor weight diff between 70 and 100 lbs. The difference in deck height won't bring your center of ballance up much.

I don't recall how much torque I'm making, but I think it was somewhere just over 500 ftlbs.

My motor is standard stroke, the increased displacement comes from the bore. My motor is built to spin, I wanted to recreate the sound of the original cars, just with more hp. Besides, it's not like these are heavy cars. My wheels spin any time I want them to. Don't really need any more torque. Heck, I don't need the torque I have.

For yucks, I looked on another Ford site...they're getting 425-450 bhp on pump gas out of 347s. Of course, I don't know how much they've spent on internals or heads, but another 75 to 100 bhp with the same compression limits seems like a lot to ask for. Hope it works.
Click to expand...

Hi Ron

The standard stroke big bore 351 definitly has appeal, hence my questions. From what i have read a complete 351 weighs 100lbs more. If ablock is even 50lbs more its on top as the weight comes from the taller deck. Plus the reciprocating mass is heavier too.

With a aluminum 302 block and light weight callies crank, olive rods diamonond pistons I think there is a saving of 180 or so lbs.

It laso depnds what block you have motorsport dart dart sportsman, they seem to have a40 or so lbs weight variance.

Butr yes if one went with an aluminun 351 block and lightweight internals with clevland journals the weigth difference might be on the order of 70 or so lbs maybe less.

Either way as you say its a light car, certainly light for the power. To me less weigth equals better braking and cornering, although maybe 100 lbs with this power is imaterial. But 200lbs is the weight of a passenger. Hard to say as I have only ever driven one Gt40 and that was a pukka 427 big block, yeah I loved the way the power came on, hence the continued interest in a 351 style motor. Can you let me have more info on your motor and who built it?

There are two types of 347's. One type has a 3.4 stroke and close to stock bore, the other type has a 2.25 stroke and a 4.125 bore which is possible to do with a dart block. A 3.4 stroke 347 with hydraulics is a 450 hp motor. But if you are running hydraulics and rev limited then might as well do both the big bore and big stroke 302, a 363 of which even ford sells a 500hp version.

So if one does a big 4.125 bore and a 3.25 stroke with solids and great heads like afr 205s then 525 hp is apparently attainable on pump gas with a 347, plus its supposed to be really snappy. With race fuel and 14.1 a 347 is over 600hp. Of curse no 347 is going to have the robustness and longevity of a 351 based motor. But if it lasts 15k track miles before refreshing I am ok with that.

That all being said a great 351 with great internal balance and revable does sound appealing.
How many miles have you done so far, before you are looking at the valves.
 
B

Sean

Keith1 said:
Be careful you don't mix data from the Goodwood Festival of Speed with The Goodwood Revival, they are held on different tracks. FOS is a hillclimb sprint - Revival is held on the race track proper.
Click to expand...

Yes the hilclimb is the Driveway, under 1 min for pretty much any fast car. I am refering to the GT40 race that was just held at goodwood on the track. There is a video with Kenny Brack in the rain, even in the rain he was doing 1.40, but earlier in the dry he did 1.22, which seems really fast compared to some of the street cars listed, but then the Lola t70 did a 1.18.

There are alo two types of laps, standing start and flying laps. Most laps timed for streetccars are standing start which are naturaly slower. I belive the streetcar laptimes I have are the best of 3 laps flying start so comparable. It seems Goodwood though is a track that really benefits from Hp.

on the hillclimb the new 14 Gt3 supposedly did 45 secs.
 
I

Ron R.

Sean,

I've got about 500 miles. The valves were checked early on by the builder. But its time to do it again.

I'll put up my dyno sheet today, I had to work too late last night to dig it out.
 
K

Keith

Moderator
I believe anywhere between 8 and 10 minutes for "street" GT 40 replicas depending on state of tune and driver commitment. There is a video on here of the UK Club's "Assault on The 'Ring" which is interesting to say the least. Perhaps a dozen or so cars at one time.
 
B

Sean

Keith1 said:
I believe anywhere between 8 and 10 minutes for "street" GT 40 replicas depending on state of tune and driver commitment. There is a video on here of the UK Club's "Assault on The 'Ring" which is interesting to say the least. Perhaps a dozen or so cars at one time.
Click to expand...


I guess then the question would be, what time would an equivalent driver do in say a M3 of Gt3, or what would Sabine Schmintz do in a Gt40.
Have there been any historic races there with Gt40's lately.
 
K

Keith

Moderator
There certainly are Dutch, Belgian, French & German members of high calibre driving skills that have done this. Would suggest you pose a suitably titled new thread on 'Race Track' forum as they would not necessarily monitor this one.

Yes, I would do Sabine as well although not in a '40 :)
 
B

Sean

Found some more times.

On the 2011 version of the Ring grand prix circut a race GT40 did 2.16, have no idea of driver or spec.

A porche Gt3 did 2.19 also no idea of driver or spec.
 
2

Julian

A 'GT40' will do whatever time around a track you want it to. Same as any other car with similar potential. How much money do you have, how much time have you got to develop it and how much skill do you have? These factors apply to any competition situation.

My DRB GT40 goes very well in competition, but I built it for that. So it's no fun to drive on the street. Sure it could go faster, if I had more money/time/skill.

By comparison my friends RF GT40 I drove recently was a complete pussycat on the street, very nice to drive. But would be useless on the track.

It all depends on what you want from the car. A GT40 is a very good competition car layout. It ticks all the boxes, apart from downforce, which was pretty well unknown during its gestation. But it looks better than pretty much anything on track and sounds better too!

I've competed against all sorts of cars you mention. Z06 vettes, Viper ACR, GT3 Porkers, modified Elise/Exiege's with lots of power, Nissan GT-R's and pretty well every EVO and WRX. And you know what? The GT40 is competitive, or at least a DRB version is. It will match or beat the above cars, depending on the course and how well I drive on the day. And this is against good drivers, I'm ignoring ones who can't drive for this assessment. This is with a 380 RWHP 347 Windsor motor, 17" rims and modern R comp DOT tyres. Motor is a good one, but not one that's had large amounts of development money or time. Just a summitracing parts bin special that does the job.

So there you go. It can be done and done well.
 
B

Sean

200MPH said:
A 'GT40' will do whatever time around a track you want it to. Same as any other car with similar potential. How much money do you have, how much time have you got to develop it and how much skill do you have? These factors apply to any competition situation.

My DRB GT40 goes very well in competition, but I built it for that. So it's no fun to drive on the street. Sure it could go faster, if I had more money/time/skill.

By comparison my friends RF GT40 I drove recently was a complete pussycat on the street, very nice to drive. But would be useless on the track.

It all depends on what you want from the car. A GT40 is a very good competition car layout. It ticks all the boxes, apart from downforce, which was pretty well unknown during its gestation. But it looks better than pretty much anything on track and sounds better too!

I've competed against all sorts of cars you mention. Z06 vettes, Viper ACR, GT3 Porkers, modified Elise/Exiege's with lots of power, Nissan GT-R's and pretty well every EVO and WRX. And you know what? The GT40 is competitive, or at least a DRB version is. It will match or beat the above cars, depending on the course and how well I drive on the day. And this is against good drivers, I'm ignoring ones who can't drive for this assessment. This is with a 380 RWHP 347 Windsor motor, 17" rims and modern R comp DOT tyres. Motor is a good one, but not one that's had large amounts of development money or time. Just a summitracing parts bin special that does the job.

So there you go. It can be done and done well.
Click to expand...


Thank you, this was the type of direct feedback I have been seeking,
Would you care to share spring rates and shocks. Also what brakes do you have.

My thought is to have 17 in rims with hoosiers for the track, 600lbs springs, but adjustable shocks and a set of 15 in wheels so it can be somewhat streetable.

I am tending towards the aluminum 347 route, with solid lifters(this may be overkill).

I understand no downforce, but if the rest is good that is fine. Lets face it the modern stereet cars have downforce to the extent they eliminate lift, and maybe some positive at ultra high speeds, the type of which are mostly unatainable except on a very long track.

Yeah drivers are the single most important variable. But if it takes a few years to really learn the car a opposed to having modern electronics do the learning that is all part of the fun and skill. It took me about 30 track days to really undertand my Elise so that it was like a well worn glove, and I am sure that in another 30 days I wuill still be learning more in that ca..
 
B

Sean

Igofaster said:
Thats only early on. Will also need to check the heads etc. After the engine has been broken in, the intervals will be spaced out significantly....except when tracking the car :thumbsup:.
Click to expand...

Is it worth it to have solids? or just better to have a slight power and rev loss and go with Hydraulics.
 
2

Julian

Sean, my suspension setup is meaningless to you unless you own a DRB, as I'm sure the geometry and wheel rate vs spring rate willl be different between that and a SPF. If you could give me all the suspension measurements for a SPF then I could give you all the comparitive data, but even then my settings are just a guess and I'm happy with them. Why not ask someone who races SPR GT40's. That's what I'd do.

As for brakes, well I'm pretty sure the standard SPF setup will be fine with appropriate pads and quailty fluid, but obviously if you went for 330 mm discs and 17's you'd have more stopping power for longer. I run 330 front discs and 290 rear discs, 4 piston calipers all round, balance bar, no power assist.

Buy a GT40 and rest assured that it will be as fast or fun as you are able to make it, same as any other car. Forget all your worries about what motor to run. You can change cams and lifters as many times as you like.

Just get a car and get on with it already!
 
B

Sean

Car comming from SA sometime in March April. Figure another two months to assemble/sort. Hopefully I will have it around Mid June, which also happens to be my 50th birthday.
 
I

Ron R.

Boxerman said:
Is it worth it to have solids? or just better to have a slight power and rev loss and go with Hydraulics.
Click to expand...

Everyone has to make that determination for themselves.

I used to have a Kirkham (Cobra) that made 511 BHP at the flywheel. I know that many people think that kind of horsepower is overkill, but there were too many times I wished I had more.

The GT40 was to be my personal "ultimate car", and I didn't want anything to be lacking. My goal was to have a motor that sounded like the originals, and part of that was to be able to really wind the thing up. After my experience with the Cobra, I also had a personal horsepower target of 600.

Do I need that kind of HP? Of course not. Can I use that kind of HP? 95% of the time, no.....But, Oh, that last 5% makes it really worth it. :thumbsup:

For me, I had to go with solid lifters to reach my HP target without going crazy in other areas of the build.

PS, I will post my Dyno sheet, I've just been working crazy hours lately.
 
You must log in or register to reply here.

Similar threads

C
New Guy Here; Hopeful for a Weber 289 48 IDA Baseline Recommendation.
Replies
7
Views
2K
crazycaseys53
C
B
Noob Motor questions
2
Replies
27
Views
5K
SwiftDB4
S
B
Noob questions
2 3
Replies
45
Views
7K
jac mac
J
P-nut
“Looks like you brought a grenade launcher to a gun fight”
Replies
9
Views
3K
RX-Heven
R
Ron Earp
March Memories VIR 2009 - A 260Z Outing
Replies
8
Views
2K
Big-Foot
Big-Foot
Back
Top