Boost and HP quess

[91Supra313]

Ok so, here is a question for the masses. With my next setup, I am trying to find out how much boost I could run and what power I should expect from it. Here is what I will have done. I just want to know if it will even be worth it for us.

from top to bottom

BC valves
Ferra springs and retainers
BC cams
Titan Cam Gears
JE .40 oversized pistons
Eagle H beam rods
ARP bolts and studs all around
Clevite 77 bearings all around
HKS Stopper 2mm
Master Power T70 (1.15 hot side/? cold side)
Custom Manifold
Tial wastegate
Blitz NUR Spec 3"
custom 3" IC pipes
not sure of IC yet
Walbro 255
RC 550 injectors
Aeromotive AFPR
Apexi AVC-R
possibly a MAFT-Pro
GReddy/Trust Type R bov
Aluminum drive shaft


Machine work to be done

5 angle valve job
CNC combustion area on head
Port and Polish head
Port Match to intake
Block bored 40 over
crank polished and balanced

I might have missed a few things on the list, but as I remember them I will add them. I just want to know what a safe estimate on the boost could be. High limit basically. If it is around, oh I don't know, say 20+ psi, what type of power am I looking at? I would really like to get up around 500+ if possible.

 

[IJ.]

+60 bore is going to be a limiting factor, which block is this built on?

 

[mk3_supra]

+60 bore is going to be a limiting factor, which block is this built on?

was wondering that too, if this is on the 7M my understanding was +40 was the limit?

 

[IJ.]

was wondering that too, if this is on the 7M my understanding was +40 was the limit?

Depends if it's an early or late block.

 

[91Supra313]

Sorry I forgot to put that in there. Yes it is a 7M block. The block is a December 1988. As far as I know. If it has been changed....no clue before me.

 

[DigityD'87]

235hp @ 6psi

 

[IJ.]

Good chance it's the thin block, check the sticky in GTE Tech for the differences.

 

[91Supra313]

235hp @ 6psi

Not quite sure where this one came from but thanks for your HP numbers.

Good chance it's the thin block, check the sticky in GTE Tech for the differences.

Thanks IJ I will check on that one for sure!

 

[IwantMKIII]

.60 over? why? How many times have you rebuilt this thing? lol

 

[91Supra313]

.60 over? why? How many times have you rebuilt this thing? lol

I'm doing it 60 over to increase the bore. That has nothing to do with how many times the engine has been rebuilt. I'm just increasing the bore to 84mm instead of the stock 83. That way the motor is just a bit larger then the stock 3.0

 

[IJ.]

1mm= 40 thou

The increase you get from an overbore isn't worth the effort/expense, much better to keep the walls as thick as possible and dial in a little more boost.

 

[Poodles]

1mm= 40 thou

The increase you get from an overbore isn't worth the effort/expense, much better to keep the walls as thick as possible and dial in a little more boost.

THIS ^^

The difference is going to be minor, only overbore as much as you need to to clean up the bores.

 

[91Supra313]

Well if overboring it only makes a minor difference, how come all of the big block racers do it? Not trying to be an ass on this but I seriously want to know if boring it out would help with the power gains.

 

[whitemike]

Yikes

 

[IJ.]

Well if overboring it only makes a minor difference, how come all of the big block racers do it? Not trying to be an ass on this but I seriously want to know if boring it out would help with the power gains.

8x 4.250" Cylinders once bored actually give a good displacement increase i.e.: +60 427ci = 440ci or +13ci , 6x 3.26" @ +60 will only yield =7ci and the actual HP increase from that would barely be measurable on a chassis dyno.

A +60 Early block is going to have very thin walls and will suffer localised hot spots and poor cylinder sealing so will probably make less power than a stock block with 1psi more boost.

At a bare minimum the block will need to be Sonic Checked for any Core shift or Water jacket erosion before going that large and even then I'd highly recommend NOT doing it.

This is based on 30+ years of playing with high performance cars/engines so take from that what you will it’s of course your engine.

 

[Nick M]

I'm doing it 60 over to increase the bore. That has nothing to do with how many times the engine has been rebuilt. I'm just increasing the bore to 84mm instead of the stock 83. That way the motor is just a bit larger then the stock 3.0

It has everything to do with rebuilding and almost nothing to do with performance. In the case of a small engine like ours. You do not have a 500 cubic inch engine, yours is 180. Do the math. That takes you to just over 184 ci, from 180. If you were running that Kieth Black Olds big block, sure take it out as much as you can for as much displacement as you can. Not a production block.

It sounds like a very thourogh build. Be sure to have some results when this is done. Bowl work goes a long way on most engines.

 

[91Supra313]

I think I will go with what IJ is talking about and leave the bore and maybe just go 20 or 40 at the most. Original post change to .40 over. Now that this issue is out of the way, back to the original thread topic please. What type of Boost should I be able to pull from it? Also depending on the boost of course, with the mods listed, what type of power might I expect.

 

[oldsking]

With the right tune (equal fuel to air ratio) you should see the 400 range close to 500 but you have to have it tuned right

 

[Cz.]

Doesn't look like it should be too hard to hit 500whp with those mods, though the 550cc injectors will be getting maxed out. Those plus the single walbro will be holding you back if you want more.

 

[BlackDevilSupra]

What are the spec's for a Master T70 turbo? Compressor wheel's inducer / exducer size, and similar spec's for the turbine wheel?