turbo question's - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*low&slow* · 10-09-2012, 03:58 PM

I have a friend who wants to put a turbo on his small block v8. He wants to know if he should build up the bottom end of the motor or the top end?

He isn't looking to build anything too crazy. He wants around 400 hp, but still get decent gas mileage, at least 10 mpg.

His motor is stock right now. He has it completely torn apart and is getting ready to build it. Although he does have a set of heads that have bigger intake and exhaust valves than a normal small block head has.

As for the heads, he is getting about 8:1 compression and wants to know if he shaves his heads, will that increase his compression any at all?

Also he wants to know if he should just leave the heads as they are and get domed pistons? Or shave the heads and get domed pistons?

BigDan3131 · 10-10-2012, 02:38 AM

The best source of info is here: http://www.theturboforums.com/smf/index.php Every turbo question you can ask has probably already been answered there.

Marv D · 10-11-2012, 09:36 AM

Heads, cam, intake / exhaust flow.... all our regular thoughts go straight out the window when you start forcing air down the throat of a motor. When it's force fed,, why would you need some head capable of flowing 300+cfm at 1 atmospheric pressure when you can create 6 or 7 x the PSI with a simple reprogram of the BOV or twist of a wrench on the wastegate.
Build the bottom end for 600+HP and it should survive 400 forced induction with ease. A QUALITY forged piston is a must here.

*low&slow* · 10-13-2012, 02:22 PM

Awesome. I will let him know what you all have to say.

As for a Quality piston, what would you recommend?

Marv D · 10-14-2012, 09:51 AM

SRP is the 'shelf stock' line from JE and is easily a 700+HP piston. They just are ran as 'the most common order' and may not see the extent of tooling a JE does. But Just stay away from the hyper-u-cracked it and ANY form of power adder and the motor will live a lot longer healther life

*low&slow* · 10-16-2012, 03:43 PM

Alright, so as far as pistons, I know there is a lot more to a bottom end. My friend wants to know about cranks and piston rods? What brand would be the best to go through for quality made parts?

Thanks for all the help so far Marv.

Marv D · 10-17-2012, 08:54 AM

I like Scat cranks,, their ductile iron street cranks are decent for a n/a - driver setup, and they offer anything you want up to the $2000 Pro-lightened trick deals tolerant of 1200hp. Scat and Eagle are forged in same offshore foundary (as is 90% of the cranks these days) . Eagle finished there, Scat shiped here for final machining. Howards,,, Crower both reported to come from US foundary... only a few I know if still forged in the US unless you get into the ultra upper end stuff like Bryant etc.. Any more I don't think it matters 'whos' crank, it still needs to go to a competant engine 'builder' to be checked for straightness, journals and cracks. It's amazing the lack of QA these days.

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10-09-2012, 03:58 PM	#1
low&slow Account Suspended Join Date: Jan 2009 Location: Kuna, Idaho Posts: 1,046	turbo question's I have a friend who wants to put a turbo on his small block v8. He wants to know if he should build up the bottom end of the motor or the top end? He isn't looking to build anything too crazy. He wants around 400 hp, but still get decent gas mileage, at least 10 mpg. His motor is stock right now. He has it completely torn apart and is getting ready to build it. Although he does have a set of heads that have bigger intake and exhaust valves than a normal small block head has. As for the heads, he is getting about 8:1 compression and wants to know if he shaves his heads, will that increase his compression any at all? Also he wants to know if he should just leave the heads as they are and get domed pistons? Or shave the heads and get domed pistons?

10-10-2012, 02:38 AM	#2
BigDan3131 Registered User Join Date: Jun 2006 Location: Maple Valley, WA Posts: 1,913	Re: turbo question's The best source of info is here: http://www.theturboforums.com/smf/index.php Every turbo question you can ask has probably already been answered there. __________________ Custom Painter/Restoration Specialist 1965 GMC 3/4 Ton LB SOLD? 1964 Chevy El Camino in full restoration 1991 Chevy S10 288K+ miles 2nd Owner SOLD 2020 RAM 1500 Warlock

10-11-2012, 09:36 AM	#3
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: turbo question's Heads, cam, intake / exhaust flow.... all our regular thoughts go straight out the window when you start forcing air down the throat of a motor. When it's force fed,, why would you need some head capable of flowing 300+cfm at 1 atmospheric pressure when you can create 6 or 7 x the PSI with a simple reprogram of the BOV or twist of a wrench on the wastegate. Build the bottom end for 600+HP and it should survive 400 forced induction with ease. A QUALITY forged piston is a must here. __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

10-13-2012, 02:22 PM	#4
low&slow Account Suspended Join Date: Jan 2009 Location: Kuna, Idaho Posts: 1,046	Re: turbo question's Awesome. I will let him know what you all have to say. As for a Quality piston, what would you recommend?

10-14-2012, 09:51 AM	#5
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: turbo question's SRP is the 'shelf stock' line from JE and is easily a 700+HP piston. They just are ran as 'the most common order' and may not see the extent of tooling a JE does. But Just stay away from the hyper-u-cracked it and ANY form of power adder and the motor will live a lot longer healther life __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

10-16-2012, 03:43 PM	#6
low&slow Account Suspended Join Date: Jan 2009 Location: Kuna, Idaho Posts: 1,046	Re: turbo question's Alright, so as far as pistons, I know there is a lot more to a bottom end. My friend wants to know about cranks and piston rods? What brand would be the best to go through for quality made parts? Thanks for all the help so far Marv.

10-17-2012, 08:54 AM	#7
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: turbo question's I like Scat cranks,, their ductile iron street cranks are decent for a n/a - driver setup, and they offer anything you want up to the $2000 Pro-lightened trick deals tolerant of 1200hp. Scat and Eagle are forged in same offshore foundary (as is 90% of the cranks these days) . Eagle finished there, Scat shiped here for final machining. Howards,,, Crower both reported to come from US foundary... only a few I know if still forged in the US unless you get into the ultra upper end stuff like Bryant etc.. Any more I don't think it matters 'whos' crank, it still needs to go to a competant engine 'builder' to be checked for straightness, journals and cracks. It's amazing the lack of QA these days. __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.



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