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turbo vs. non

deezl duly

deezl duly

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Location
riverside ca.
hey guys, just bought a super clean long block from teds in alabama. im new to the 6.5 and was all excited to finally get this motor, (due to the fact that the one in the truck i got was ruined by spun mains.) and after i dropped it in i was informed by a guy from n.y. that the compression may be too high if it was a non turbo motor.my question is,how can i be sure that was or wasnt a turbo. an engine builder in my area says that the pistons are the same in both, so if in fact the compression is too high, can i lower it with heads from the turbo motor that came out of it?any help would be great,not sure of the year, but teds said some of you had used them in turbo applications. thanks in advance.
 
You'll be fine. Just swap everything over from your damaged longblock to the new long block. You'll need to change the passenger side valve cover so that you can install the CDR/tuna can. Other than that, you should be good to go.
 
Well at least you will get good info here...

Compression is a non issue at the low boost the GM turbo uses around 6 PSI up to 14 PSI before the turbo chokes and becomes an air heater. 20:1 or 21:1 for example isn't a big deal. Far as I know 6.5's have the same compression. 6.2's have higher compression.

Now the big deal is the pre-cups in the heads.
NA engines have a different precup then the turbo engines. 6.2 precups are different as well. Worst case is running 6.2 precups with a turbo. My 1995 and 1993 both have 6.2 precups and 6.2 heads. Only difference is 3 MPH at 65 MPH pulling a trailer flat out. 6.2 being slower. The NA precups on the 6.5 turbo engine did not make a difference - My 1993 Chevy had a NA 1995 6.5 in it that was worn out see pic. MPG is the same for all 3 configurations towing for me.

On the left is a head with Military precups on a 1986 6.2, 3 bars. The cups sitting on the head are 1995 turbo precups, round dot. The head on the left is NA 6.5 precups, square mark.
precups.jpg

Bottom line is you are not going to notice the precup difference or compression difference if there is one. :agreed:
 
thanks for the info what drew my attention in the first place was the r/s vaive cover. thats when i started asking and got the (too high comp theory.)im very releived cuz i finally have all the parts to get this thing going. thanks again, ill keeep ya posted
 
The square precups aren't necessarily for NA applications. My original motor had square precups from the factory, AFAIK. At least that's what I pulled out of them when I had it apart last spring.
 
Make sure you have a good set of high pop 6.5 turbo injectors. Test yours or get them rebuilt. Don't spend less than ~$65.00 each for good new/rebuilt injectors. Cheaper last about 30K miles. Ask me how I know.

Square precups are smaller, block was a bored over 1995 date code in a 1993. Figure it came out of a Frito-Lay van. The reference for precups I found claim NA use for those marks.
 
X2 it doesn't matter much what the precups are unless you are trying to break records. The injectors need to be set ~2200 psi for good fuel spray.

What are the specs on your truck? Is it the lowered dually in your avatar?
 
yea thats the truck in question. i bought a long block from teds and i put a set of marine injectors,remote pmd, and the cooling system upgrade so far. now that i have some re assurance on the compression issue ill probably try to finish it up next weekend.by the way it came with a spring type wastegate actuator from heath that replaced the vacuum pump setup.any advice on that?one guy (from n.y)told me that only a snake oil salesman would sell that unit,but ive read that some folks prefer thm. any suggestions? once again thx for all your help.
 
The TM (turbo master) has been discussed many times and is a quality product. Results do vary but I don't have any first hand experience with it.

What year of truck and what kind of drop does it have? I am just curious, it doesn't really matter for the engine questions.

Fill out your signature, it will help us help you!
 
its a1995 with a belltech spindle kit with a c-section air bag rear not sure of exactlyhow many inches but i think its 3.i got the truck that way for next to nothin with a bad motor.it shows 73000 on the odometer and as clean as the interior and body are its probably original miles.the po cracked the heads, and after he put brand new ones on spun the mains 7 miles later.thats how i ended up with it.i knew very little of the 6.5 but became quickly enamored with it.guess thats why im asking all these questions that you have answered tons of times.sorry for that ill get up to speed.thanks for all your help.
 
We don't mind answering questions but being a new member it is best to read through a few old posts to to get your bearings then it is easier for you to understand when we explain.

You might consider putting a diesel front bumper back on.

You have the truck of my dreams... Lowered, 95, CC, Dually :drool5: now all you need is 22.5 alcoas with spikes :sifone: , I like the 94 and 95's for tuning options and the 95's for the interior, perfect cruisin truck sir!
 
deezl duly said:
yea thats the truck in question. i bought a long block from teds and i put a set of marine injectors,remote pmd, and the cooling system upgrade so far. now that i have some re assurance on the compression issue ill probably try to finish it up next weekend.by the way it came with a spring type wastegate actuator from heath that replaced the vacuum pump setup.any advice on that?one guy (from n.y)told me that only a snake oil salesman would sell that unit,but ive read that some folks prefer thm. any suggestions? once again thx for all your help.
Click to expand...

Get an A Team Turbo and forget about the spring thingy and wastegates... The spring thingy replaces the vac pump and is all a trade off.
Best advice is to get a EGT and boost gauge. Keep the max boost under 14 PSI as the GM turbo becomes choked and just heats the air after that. Find the max boost at a lower RPM WOT with a trailer or brakes applied to give the engine full load that will spool the turbo the most.

Economy while at cruise is the only real benefit for the vac system. Myself I have used the spring and A-Team and prefer the larger turbo. But I work mine hard.
 
tanman_2006 said:
You have the truck of my dreams... Lowered, 95, CC, Dually :drool5: now all you need is 22.5 alcoas with spikes :sifone: , I like the 94 and 95's for tuning options and the 95's for the interior, perfect cruisin truck sir!
Click to expand...

I remember an early 90's dually I saw in Indio. Belonged to a race team and they had replaced the dual wheels with very wide single units on some seriously deep dished rims. I'd been in Germany for 6 years and hadn't seen anything like that before. Probably common now but I haven't seen one since either, even at the races. Nice find. I don't have a need for a dually but if I did....
 
Super singles are somewhat popular on big rigs but I have never seen a low profile super single tire on a pickup. That would be cool though!
 
Thats a real nice looking rig. The holes in the bumper were for a good reason though, to help keep the thing cool and direct air into the intake. So need to overcome that deficiency or get the right bumper.
 
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