OK there is a Bare LT1 Block 2Bolt on my stand I have a GM-6 Turbocharger from a GM Diesel and I have created all neccesarry things to do it. But here's what I'm wondering, ,

Straight line performance is Minimal I hate drag racing I like Road Courses so I want to Know if De-Stroking to a 327 and Turbocharging at about 4PSI would be better? I'm thinking more along the lines of a high revving driving machine as opposed to a Big Displacement torquer. Or do I just stay with a 350? Has anyone done anything like this? Seems like the 327 would be a "quicker" motor. I think I need a new Crank anyway Beacaue (if you read My Sqeaking Thread) the Rod Bearings for #'s 7 and 8 spun and sorta ground down the crank so Now starts my bottom-end Build-Up!

 

No, the 350 is the best place to start on a turbo small block.

Don't destroke a engine and spend money at it unless you are going for more RPM at the same displacement with a larger bore.

Bret

 

agreed.youd think youd want to stroke even further for a road coarse, but i may be wrong

 

I'm dooing the same thing right now but without the turbo. this will be the second engine I've de-stroked to a 327 would'nt think twice about it.
the first onewas aboutthe best chevy engine i've ever built
they can handle the revs and make awsome power

 

Was this a Gen II block you did this with and if so what hind of RWHP did you make Plus keep in mind the T56 I thinkl my crank is trashed so I'll need to make a decision also what Crank did/are you using?

 

youd need some really big bores to make destroking worth it

 

Revs for revs sake isn't logical. If you have the same heads and an optimized cam with the same bore, the longer stroke/larger displacement motor will make about the same peak hp but will make more torque. IOW, it will be a faster combo.

Rich

 

While the early 327's were good in their day, engine technology has far surpassed these older motors.

Since you are RPM limited w/ the LT1 to 7K due to the computer lmitation, there is no need to try to destroke. A decently built 350 should be capable of this RPM anyway. Cubes tend to rule in every aspect except mileage. Any gain you achieve in peak HP due to the reduced frictional losses of the shorter stroke, you will likely lose in torque at lower RPM. Torque will generally rule on the street & the strip. Road courses generally favor torque as well, with the HP numbers helping only on the long straights. To flow the same air as a 350 at 6500, you need to rev the 327 to 7k. Keep in mind that you are not onto a new idea to build a 327..... the reason there aren't more of these is they generally are not worth doing. Personally any time I buy a crank & pistons for a performance build, (class rules permitting) they are to build a 383.

Your turbo idea must be thoroughly researched as there are many turbo specs to take into consideration to be sure it will work properly on your engine. 4# boost is not going to make it a powerhouse anyway, so be careful of your parts combination as you may spend a ton of fabrication labor to build a economical low boost turbo motor that gets outrun by a N/A 383.
If you are insistant on doing this, buy a used LT1 crank & use it. They are easy to find & will live at 4# boost all day.

I don't mean to be negative, but only want you to keep from wasting your money.

 

Thanks for the info I think I will stay at 350 now. As far as Turbo, where do I find out more technical inf The GM turbo I have came off of a 6.0 Diesel and the limited research I have says that @ 4000 RPMs one side (Exhaust) will provide about 4# of boost

 

are you going to run the turbo off one side or both, That disel isnt going to have the same amount of exhaust running threw it
so i have no idea on boost

 

I have seen 4,500fps as a guideline for maximum average piston speed in a street/strip or amatuer race motor. This assumes the use of high quality "sportsman racer" or better type components and (needless to say) careful engine assembly. If you accept this, approximate max rpm is as listed below.

stroke rpm
3.25" ~8,300
3.48" ~7,800
3.75" ~7,200
3.875" ~7,000
4.00" ~6,750

Interestingly, a 325ci motor at 8,000rpm and a 400ci at 6,500 each move ~775cfm. So, if they were optimized in other respects they would make about the same hp. This doesn't change the basic limitations of rev range though. If you optimize a traditonal 2V OHV V-8 to run up to 8,000rpm, it won't be much fun at 2,000!

Rich

 

I've seen a few relatively big CID motors turning some pretty high RPM recently. How about a 428cid Gen3 motor spinning up past 8200? Or even a 514cid BBC spinning up to 9000? You mainly need very good flowing heads.

 

hm.. i might disagree... but a bit only, because i follow your logic and i embrace it, hence why i went with the 383 and didn't stay 350... But it got me thinking...thought: isn't it easier to handle and get the best performance out of a high revving engine with less torque and same HP than a higher torque engine?

Wouldn't you spin the tires a lot easier?? i thought that was what GM did with the 346, hence why the new Z06 and its 7L will have 345s on the rear tires...

The viper engine was being talked to go down from 8.3L to 6.9L on a v10. would it be to reduce the torque, up the revs and get same or more power so its easier to handle and get the performance out of it?

too much torque= spinning tires!

 

This is silly, the stroke or destroke thing is purely going to depend on the type of driving. torque is good on the street because you use power in all rpms, it wont matter at the track with your 5000rpm stall and trans brake. That is why supras with a very limited power band can go so fast. Overall i would go stroker same top end but you have bunches more torque. Why would i want to rev the crap out of my car on the street to make power. i have rode 2strokes before no power on the bottom crazy to end = not practical at all. 600 sportbikes are the same way, no torque rolling on the throttle, they dont make power till 9,000 but when your at the track your only out of power for a limited time when you launch. If you have more torque you can launch at lower rpm and keep reliabilty up. The reason F1 rev high is not because thats where the power is at, its because they have very strict limitations and thats the only way. same way with imports no cubes no power. only way to make good torque and keep rpms down is with nitrous. the only reason people rev motors that high is to cover somthing up but If they have the right setup is wont hurt them any at the strip except for reliablity

 

You have a point, and I know quite a few people who live by that moto. Amongst my friends we have those who choose to build 383's instead of 350's and 400's instead of 377's (destroked 400).

The bottom line is that those who build the larger displacement versions of motors require less stall speed and less gear to accomplish the same (or better) performance as those who choose the smaller displacement versions.
The smaller displacement versions are less streetable, require larger converter stall speeds and steeper gears to do what the larger displacement motors do on low end torque alone.

Here is a perfect example:
I have two friends, similar vehicle weights, similar solid roller sbc setups, one running a 355 and one running a 383.

The guy with the 355 runs a steeper gear and a 5000 stall, whereas the guy with the 383 runs a 3000 stall and a more streetable gear, they run the same 60' times and similar ET's.