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Discussion Starter · #1 ·
i am going to start building a twin turbo motor i have been planning to build for a while but i wanna get some advice on some engine combos that would work well and save some money
i wanna keep the stock chevy heads i got off a short block i bought and never used
should i go with a higher lift and wider LSA cam and go with bigger springs?
i already have it in the making to go with a master rebuild kit that comes with all the gaskets and a set os forged speed pros
do you think i can get away with using the stock crank?
main thing is that i dont wanna invest in an expensive set of heads when i already have a set that has never been used and i dont wanna buy an expensive crank
i just want the engine to handle a low boost twin turbo setup maybe 10psi

any advice is appreciated
 

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10 psi isn't exactly low boost. For example, new mustang turbo kits run 6-8 psi, with 8 psi being about the max people recommend for a stock block. Are you going to be running a carb, or fuel injection? I'd recommend doing some reading about turbo's before you start spending money. Maximum boost is a great starting point.
 

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Psychomotors
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Try www.theturboforums.com . Turbochargers by Hugh Macinnes(HP Books),Turbocharging Performance Handbook by Jeff Hartman(Motorbooks Workshop).I plan on using a 400 sbc for my build.Im still in the collecting parts phase,lol.I bought my stainless steel turbo headers off E-bay for $150 including shipping.I got a couple Holeset H1C for free from a buddy.I'm going to be using a 850 dp holley in a blowthru design.You can use a nitrous or blower cam with good results from what I have read.Don't let everyone tell you it can't be done,IF you are a true hotrodder you WILL find a way. :thumbup:Now about your heads-Will they work?YES.Are they the best choice?No.I had a buddy who ran 461s on a 355 with a 6-71.I told him many times that he needed a good set of aftermarket heads.It wasn't until Jim Oddy told him the same thing that he finally believed me.If you are just after the "wow" factor at car shows and cruises,then by all means use what you have.IF you're serious about REAL power, you will want a set of aftermarket heads.
 

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Listen and Learn
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10psi is a lot of boost. It will need a lot more than forged pistons, like h-beam rods, and a forged crank. possible splayed 4bolt mains. Dynosim for the turbo build i am planning on doing is set for i believe 8psi, 385ci stroker sbc, dart block and will be running upwards of 800hp with afr heads and a fuel injected intake. You never mentioned what engine this is but you said something about stock chevy heads so should i assume 350?. If this is so there is no way you can run a stock crank at 10psi. From what i have read 500hp and 6000rpm is about all stock crank are good for. From then on u r pushing the limits. What kind of HP are you looking for?
 

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I guess you are talking about a 350 chevy?

You need to find out how many cc the heads are.

I would do a basic rebuild, set up cr at 7.5 to 8:1.

use the smallest compcam turbo cam with stock springs.

use a set of 280 zx turbos (81 to 83) or a set of ford t-bird turbos. Get the turbo with external wastegates. They go for 50.00 each at the you-pull-it junk yard.

run 7 or 8 psi of boost.

it would be much better to use efi with ignition timing control but you can blow through a holley double pumper with a msd boost retard ignition.

7.5 psi will add 50% more power. so if your engine is making 300hp/330 ftlb without boost, then it will make 450hp/500ftlb with 7.5 psi of boost.

450hp doesn't sound that high but the torque is huge and comes on very early with small turbos. plus 450hp with a smooth idle is hard to get without a turbo. so it will run well with stock gears and converter.
 

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Discussion Starter · #7 ·
yeah sorry it is a 350 i pulled it outg of my corvette which i just finished a very expensive blower build on

it will be carbed an my goal mid 600 for hp as time goes on i think i should change the crank but with the lighter forged pistons the rods might be ok after the only thing that kills rod is lack of oil and too much rpm the compression stroke isnt gonna bent a rod

what heads would you guys consider?
 

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you can make 600hp with a 300hp engine plus 15 psi of boost.

or you can make 600hp with a 400hp engine plus 7.5 psi of boost.

so the more hp you start out with, the less boost it will take.

it would be cheap to make 450 to 500 hp with junk yard turbos and stock blocks and heads. But more than that gets expensive very quickly. Big Intercoolers and custom turbos are expensive.

if you a talking about using stock heads and saving money, then I would lower horsepower goals.

mild turbo cams tend to have wider lsa (112 to 114), and more duration on the intake than exhaust. 260 on the intake, 250 on the exhaust with 114 lsa will work on a mild 350 with quick spooling turbines (like a pair of turbos from a 2.3 liter ford or 2.8 liter datsun engine)
 

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Psychomotors
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I will be using Dart Iron Eagle 215s because I already have them.I've been using them right out of the box for years with no complaints.They are a great set of heads.My buddy had a set of Motown heads on his 355 that were very nice also but these 2 are the only brands I have any experience with. :evil:
 

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I don't see why Iron would be preferred. Honestly it shouldn't make much difference. If anything, I'd guess that aluminum would be preferred because they have better heat transfer and would probably stay a bit cooler.

Bottom line is that it will mostly come down to the quality of head, chamber design, etc. Everything else being equal though, I'd probably go with aluminum for heat transfer and weight savings.
 

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Pupsvette76 said:
yeah sorry it is a 350 i pulled it outg of my corvette which i just finished a very expensive blower build on

it will be carbed an my goal mid 600 for hp as time goes on i think i should change the crank but with the lighter forged pistons the rods might be ok after the only thing that kills rod is lack of oil and too much rpm the compression stroke isnt gonna bent a rod

what heads would you guys consider?

Are you using a stock block to make 600 horse?? And what crank and rods are you using for this build??
 

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Psychomotors
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Siggy_Freud said:
I don't see why Iron would be preferred. Honestly it shouldn't make much difference. If anything, I'd guess that aluminum would be preferred because they have better heat transfer and would probably stay a bit cooler.

Bottom line is that it will mostly come down to the quality of head, chamber design, etc. Everything else being equal though, I'd probably go with aluminum for heat transfer and weight savings.
I agree with Siggy :mwink:
 

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a new block is really what is necessary, along with a high quality forged rotating assembly. twin turbo is not cheap, it will never be cheap. You can use a single turbo to make 600hp and it would simplify things, but I would still keep it under 500hp if you plan on getting any life out if it wht so ever.
 
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