Just glancing through some of the NASCAR stuff and found the spec for the Toyota NASCAR V8 which are
Type: Toyota NASCAR V8
Displacement: 358 Cu.
Power: 675 Horsepower at the Rear Wheel
Induction: Normally Aspirated with 390 cfm Carburetor
Bore: 4.185 Inches
Stroke: 3.250 Inches
Compression Ratio: 12.0:1
The story said they went through 15000 GM Dodge and ford blocks measureing and spend alot of $$$ in developement to come up with the engine spec. I am not to knowledgeable about NASCAR engines but how in the heck do they get 750 engine hp(est) out of a 390 cfm carb???

 

With that small of a carb it's throttle response would be damn near telepathic. A small carb like that wont significantly reduce HP. They have limits on HP so they probably used that and made up the lost ponies elsewhere. They proably are only losing about 20-25 HP with that small of a carb over say a 650cfm.

 

Interesting too that out of all the choices they picked a 327 stroke. I wonder how hard it would be to put a 327 crank in a 400???

 

Griff
It's not a problem at all. All You do is get a 1969 - up 327 crank and some of those spacer bearings ( Comp Cams or Clevite ) and drop it in. You use a 6" rod and a set of Your favorite aftermarket pistons and @ .030 oversize, You have 353 inches. The Nascar Cup Cars have been using a short stroke engine like this for years. A Nextel Cup Engine uses a 750 carb on all of the tracks except Talledega and Daytona where they use a restrictor plate under the carb that reduces the 4 holes to the size of a dime. drops the power from 850 down to about 475. Amazingly, They do this with solid flat tappets. The Cylinder Heads are truly incredible as they flow over 400 cfm @ 28 inches ( common flow bench standard )

 

I have seen a few of the blocks I noticed the cam has roller bearings and they run sb2 heads?? Have you tried the 400 327 combination I wonder if it would hold any advantage over say a 383 or a 377 all flows being equal?

 

The common thing about these engines is that they make power past 9000 RPM. It is extremely expensive to put toghether a relatively large engine that can be reliable at those RPMs. Way back Chevy developed the 302 engine for the TransAm racing series using a 4" bore, like a 350 and a 3" stroke like the original 265. In racing trim they would rev even higher than the NASCAR engines and put out close to 500HP, and hold toghether.

 

The 353 deal works well in a cubic inch to weight package when You're building a class drag car. In an application where there is no rules, go with cubes all the way. I've built quite a few of the 353's for oval track but I prefer a bowtie block. THE 400'S Work ok though.

 

the bore limit in the NASCAR truck series as well as CUP and Busch is 4.185 and thats why the corrosponding stroke. we (the engine builders) did not pick our stroke first then match the bore to get our final cubic inches but the exact opposite we optimized our bore then cut our crank to a stroke that would get the correct cubic inches.

big cubic inches versus small ? well dollar for dollar it is easier to build HP with bigger cubic inches but with the rpm that we are running today we could not make one last for 500miles at 9 grand with a big stroke.
its a hard comparison big stroke will run better down low and short stroke will turn rpm and make better power up top.

ill let you all know a real world comparison soon, as we have taken an SB 2 top end from one of our race engines and finish putting together a 427cubic inch small block with that top end on it,......FUN !Lafferty Performance

 

That will be a interesting compairison cant wait to see the results!!! By the way welcome to the forum it is great to have a NASCAR engine builder here!!!!

 

Being that NASCAR chose the bore it also kind of dictated the stroke to meet the cubes then. Do most run the same stroke? In another part of the forums (Lt1) we were also discussing the 4/7 swap cams what is your opinion on them?