Ok, So The turbo on the left is a TO4E as you can see the turbo on the right is a lot larger...
My plan is to run a remote setup...Sequentially like the Supra using the smaller turbo to spool up the larger one..

Everyone keeps telling me it won't work (they think) but they are not sure...So I thought I would give it a try...

I am looking for thoughts and or suggestions here. By the way this is going on my 87' GTA T-top, digital dash. I have a newly built 350 4bolt main 40 over, RV cam, 2.02 and 1.60 valves, 10.5 to 1 compression, with a fully ported and polished (inside and out) SLP runners, manifold, plenum, 58mm throttle body, 1.6 roller rockers, 30lb Accel Injectors, Edelbrock Tri-y's, High flow 3' cat, 3' cat back

 

This is the exhaust side 5' on the big one

 

You are going to put a blower on a motor with cast iron heads and 10.5:1. Not to mention that camshaft is way too small for that kind of setup.

 

what do you mean my cam is to small its more agressive than the stock L98 and yes I am running cast iron head again stock is cast a people are turbo'ing them. Mine are just larger

 

"RV cam" is a generic term for a smaller camshaft on a wide LSA- probably 112 or 114. You are going to have an extremely high DCR with 10.5:1 and a camshaft that isnt bleeding off any cylinder pressure. On top of that, a cast iron cylinder head will retain more heat- all of these means detonation. Detonation and stock parts don't go well together.

Yes people turbo and supercharge motors with cast iron heads- they also have about 2 points less compression than you do.

 

There is a guy at the track with a BBC running 10-1 compression with a 96 1/2 trim turbo running 13lbs of boost....Now I dont know how it is staying together but it is and he even said he has the cheapest set of felpro gaskets he could find...I have seen him run at 10 sec. 1/4 spinning his tires most of the way

 

Its not going to work.


why dont u just build a motor that could support the bigger turbo.

 

I dont know how it is staying together either. The first detonation your (i am assuming) cast/hyp pistons see they will frag.

 

Ok, so now that we've got the bashing out of the way does anyone have ANY useful suggestions

 

those are useful suggestions. your not listening is all. why don't you listen to some of these guys? they know what they are talking about. if you put boost on an already questionable motor, your going to end up with BIG problems. the c/r of the motor you have now is a little on the ragged edge of being able to utilize pump gas n/a, let alone with 10lbs of boost. your pistons will be destroyed at the first sign of detonation. then the ends of your rods will beat a hole in your block. probably sending all kinds of good stuff out your exhaust, taking out BOTH turbos. build a motor with good stuff and match your heads and cam to that single larger turbo. you'll be infinetly happier in the end.

 

it'll work on race gas

you'll need to feed the big turbo into the the little one...

 

 

i honestly don't see 10lbs working well on an iron headed 10.5:1 c/r motor even with race gas. i see lots of blown head gaskets and broken pistons in the near future of this motor.

 

live n learn

 

I hate to say it, but this looks like trouble.

First of all, I don't think you are quite understanding the complexities of making a true sequential turbo system. A STTS (Sequential Twin Turbo System) will require a multitude of valves and actuators in both the compressor and turbine plumbing, plus some form of control for these valves in order to provide proper response and peroformance.

The basic idea of a STTS is to force all of the exhaust at low RPM through the smaller (primary) turbo to provide a low boost threshold. You also need to plug off the inlet of the large (secondary) turbo at this point to keep the pressurized air from the small turbo back-feeding through the large turbo. Then, once you start reaching a point where you are maxing out the primary turbo, you need to smoothly transition to the secondary. This means you need to need to start feeding exhaust to spool the turbine on the secondary turbo, and at the same time start opening the valve on the compressor discharge to allow it to start feeding the intake. At some point, you will be in full TT mode, with both turbos pumping together into the intake. FWIW, both the Supra and RX7 use turbos that are sized the same, just that they spool only one at low RPM, and both at higher RPM.

Or did you just want to stage the turbos? The only reason you would run a multiple stage turbo system would be for extremelyy high pressure ratios (boost of 30psi plus), which wouldn't be the case here. I just want to make sure I understand what you were planning.

More on STTS:
Supra- http://www.lextreme.com/sqtt.html
RX7- http://www.fd3s.net/non-sequential.html

Ok, if you read all that and still want to do your sequential system, you are more ambitious than I am. All the guys that have these sequential systems (Supras, RX7s, ) ditch them for a properly sized single turbo for better performance, so why would you want to build one anyway?

Even with a remote mounted turbo that is properly sized, you could have full boost by 2500rpm. If you go with a standard turbo system, you could probably start getting boost before 2000rpm. I see absolutely no reason to go to such an extent to try to minimize lag in a performance application (I mean when was the last time your were racing and had your Rs below 3k???).

Second, your engine combo is certainly in question, as stated above. You may be able to get away with some boost if you have everything set-up right. This means a properly sized turbo (ditch those turbos you have and sit down and calculate a correct match). A properly sized turbo will give a minimum amount of charge air heat because it will be operated at it's peak efficiency. I'm not saying you can't go with twins, but just do a standard TT system and forget all the sequential garbage. Don't just pick up turbos that 'look' right- a poorly sized turbo will give you serious lag and a scorching hot intake charge. A hot intake charge is the last thing you want on a detonation prone engine like you have.

Run a good intercooler to further lower the intake charge temps. You may want ot also consider a water injection system.

Third, you didn't give us an application for your car. What are you going to use it for? Any HP/performance goals? Also get specs on the cam. This info is going to be very important in helping you out. Give info on the turbos as well so we can see if either will be sized close for you.

Finally, all the info above wasn't meant to discourage you. I just want to make sure I point you in what I feel is the correct direction. Give some more info, and we can help you pick a properly sized turbo(s) for your goals. I just feel you need to do a bit more research before you dive in. Get both of those turbo books- 'Turbochargers' by Hugh MacInnes and 'Maximum Boost' by Corky Bell, and then read them both cover to cover at least once- I still refer to mine often (they were an excellent investment IMO).

 

beyond everything else you need a lower compression and i think having forged pistons would help...8:1 compression is usually the ideal compression for running a turbo and retard the timing as well

i dunno man maybe you should go with supercharging if that suits your motor more...i know it must be a let down to hear that your new motor is going to take a lot of new parts to do a good turbo setup but thats the ropes

replacing the parts shouldnt be impossible by any means just time consuming...shoot 100 shot of NOS and you can get a close addition of power to a turbo

im not saying its the same im just saying another way to add power very cheaply besides expensive turbo setup or supercharging

 

Some combination of race gas, only seeing boost past the engine’s power band, being full of ****… I’m guessing a little of all of that, probably a combination that was running about ½ second slower in the ¼ without the turbo and then a big enough turbo that it doesn’t spool till way late, way after the rpm range where you’ll see the highest BMEP.

What the hell is a 96 ½ trim turbo anyway?

you’re getting the answers you’re getting because people are looking at what you posted and can’t even decide where to start with where you’re going wrong. Hell, do you really think a turbo with a 5” outlet will spool as a rear mount at all? I’d bet that you’d have problems spooling it mounted right on the manifold, and if you did it would most likely only be efficient in a range that would be useless for your engine. You won’t have room to mount it, plumbing would be a nightmare if you plumbed it as a sequential. It doesn’t sound like you have any clue about what you’re getting into wrt detonation and engine controls… I’m sure if I wanted to sit here and actually think I could probably come up with at least a dozen more issues.