[Project89]

Originally Posted by F-BIRD'88

Low cr is your friend if you want to run big boost on pump gas.

there is so much misinformation about turbos on this board its not funny

u can run 9.5-1 compression and run over 20 psi of boost on pumpgas, its been done tons of times


if u want real turbo advice check out the turbo forums, and btw that ebay gt45 is not sized the same as a true gt45 turbo its actually nothing more then a 70mm turbo with a larger turbine wheel, will still make plenty of power though 650-750 should be reachable with it

i can first hand show u a engine with crappy small valve truck heads and a tpi intake that has gone 9.17 1/4 mile in a firebird
2 bolt main block
truck heads ( non vortec)
224/224 summit cam
tpi and 2 grand national turbos

thing runs pump gas and is street driven without issues

btw those 4.88 rear gears are going to make it feel like a slug, some 3;73's will make a huge difference alone

[Pupsvette76]

ive been on the turbo forums either no one repsond to ur thread or u get a jerk repsonding whole just wants to talk crap... nonetheless im looking for advice as to ideas on why this motor feels lacking not so much on the turbo theres no debate on if an aftermarket set of heads is better than stock i plan to change it would u agree the lower the compression a bit in order to run more boost is a good idea? what do u thiink about copper head gaskets for a boosted motor

[F-BIRD'88]

u can run 9.5-1 compression and run over 20 psi of boost on pump gas, its been done tons of times

Yes WITH INTERCOOLING....

Not going to happen unless and until you get the charge air temp down.
That requires intercooling or water/methanol injection.

They only other way to run big boost without intercooling is to run a very low compression ratio.

The aircharge temp from the turbo at 20PSI boost will be approaching 200°F
On a 80°F day

Its pure physics.

"small valve truck heads" could very well be a beauti set of 041 castings
ya they primarily came on truck motors.

These "truck heads" are equal or better than the famed 461-462 fuelie heads

When these are home ported they flow over 240cfm. That a long way from the crap the poster is working with.
180 to 185cfm in 115 cfm ex. Thats what he has got.

Another example of a small valve truck head is the 305HO head
#4416 I get over 230cfm from these heads by home porting them.
These 416's come on trucks too.

So do 062 vortecs 059 305 vortecs, 083 TPI heads etc
The tpi heads can be ported to 260+cfm.

This is probabily what the 9sec motor has as the TPI manifold bolts to them.

These heads are ALL "TRUCK HEADS" and all are miles ahead of the crap the poster is trying to use.
Any 14 year old who can tweek a mini bike can do a pretty fair job home porting these factory heads.

There is no free lunch. You need head flow to make the kind of power you are talking about.

Right now the gears are the least of his problems. Untill you actually start makeing some horsepower, no point in changine the gears.

You are working with a 160HP cylinder head.
NO BS there.


Copper head gaskets will not fix it.

Get some better large chamber heads and port them yourself.

There are many many to choose from.
EG GM 76cc 920, 441 487 336 EG World products sportsman II WP S/R torker 76cc.
RHS iron lightening 200

The $50 GM 920's will port up over 240cfm and 190++ by home porters ex Pros get a lot lot more.
2.02x 1.60 valves. You should be able to completely build a set for under $500.
You can buy rebuildabe one for $50. They are "truck heads" too.

The one thing you are dead right on about of the 224-224 114 summit cam swap.
The 234 cam is a bit too big.

I bet that 9sec firebird is using a efficient air to water intercooler, cooling down the charge air temp
to BELOW AMBIENT temp.

You say you can show it. Post a link where it is discussed in a forum or other web site BY THE OWNER OF THE CAR.
I know its possible and I know what it takes to achieve that level of performance.

Yup the twin Buick GM turbos work very well. (TWIN being the key word.)

[F-BIRD'88]

If you want to work with a 64cc cylinder head that can be opened up to 69cc

Change the pistons to a dished piston. There are many many many good 72++cc heads to work with.
All the stock ones will require porting

[Pupsvette76]

Inside I all the nonsensical bickering I'm hearig to change the head... I looked at the world s/r torquer heads I believe they are 195cc int runners with 76cc chambers going back to my questio would u suggest using a thicker head gasket maybe copper in order to lower compression ratio so I can crank up the boost

[Pupsvette76]

I'm not gonna start tearing down the block and rotating assembly the changes I'm looking to make are up top if I run a thicker head gasket I should theoretically be able to run a smaller chamber head like a 64cc which is more available and has more choices

[F-BIRD'88]

Originally Posted by Pupsvette76

I'm not gonna start tearing down the block and rotating assembly the changes I'm looking to make are up top if I run a thicker head gasket I should theoretically be able to run a smaller chamber head like a 64cc which is more available and has more choices

Why don;t you work on the intercooler and the water injections?

And scout for some better heads. Need not cost a lot of money. But will take work on your part.

[F-BIRD'88]

If you want a cheap head you can fix up by by home porting them and
installing decent vavles etc.
And open up the chambers too.

Look at a set of the new version 210cc Pro comp heads.
as sold by Jegs etc.
Buy a BARE SET not assembled.
The chamber is listed at 64cc but probabily bigger 67ish and you can make it much bigere,,, by hand.

Others like DR J's performance actually make a fair good cylinder head out of these
starting with a BARE casting.

You can too.
Normally I don;t recomend these china heads but........ They are light years ahead of the crap you got now and can turn out very welll with some smarts and elbow grease.
They need full home porting, full inspection and most likely a valve job.
Buy new manley street valves,,,springs etc.
The price is right.
Aluminum is much easier and faster to port and carve the chamber.

now you can make horsepower.

[Pupsvette76]

I am definitely going to add on my water inj and intercooler just wanted to try and dial in the motor in a little before hand so I have an idea if I'm where I should be and I wasn't happy with where I was at that's why I posted

[F-BIRD'88]

Originally Posted by Pupsvette76

I am definitely going to add on my water inj and intercooler just wanted to try and dial in the motor in a little before hand so I have an idea if I'm where I should be and I wasn't happy with where I was at that's why I posted

Then buy a 5 gallon pail of 110 octane unleaded race gas.

This will allow you to test with high boost and timing without scattering
that motor. What you are headed for by pushing the limit of your pump gas
with high boost and or timing (without either intercooling H2O injection or lower 7.5:1 compression $$$$$is simply a busted motor.$$$$$
The laws of physics are very stubborn. Mother nature always
wins.

[Pupsvette76]

Yeah I feel u on that one I believe u said earlier that I should lock the distributor out and set total... Are u suggesting that I try a total and give it the seat of the pants test and add or remove timing from there?

[F-BIRD'88]

You are still seeking permission from someone to push this thing till it blows,
probabily so you will have someone to blame besides your self.
The locked timing will help with that big cam, improve idle improve throttle response etc.
It wil take the timing curve out of th equation. to evaluate the real performance.
Seat of the pants will not tell you anything.
Get some slicks so you got traction. Get some good gas so you don;t bust the motor
go to the track and make 1/8 mile passes. (4.88 gears) The MPH tells the HP story.

1/8th mlle MPH x 1.27='s 1/4 mile MPH
Thats your dyno. Higher track MPH ='s more horsepower.
you need traction for meaningfull test results.

If you keep insisting on feeling your way thru this and ignoring physics all you are going to feel is mother nature slapping you up side the head, and punching you in the wallet.

I do all my power adder testing on high octane gas FIRST. You should too.

you are making this 300% harder than it needs to be.

[Pupsvette76]

im trying to gather as mch info as possible... never found that to be a bad approach and i'll stick to it...ur information is valuable however telling me about how badly i have set this this up and making remark about bow im gonna blow it doesnt

[Pupsvette76]

i will be getting some high octane fuel and locking the timing while adding a little at a time and testing ur advice is being taken

[Pupsvette76]

hey guys i need a little help for the last couplke weeks ive been trying to get my nova to perform ... its a sbc 355 with a stock small block cam stock heads single plane intake manifold powerjection 3 efi msd e curve distributor and a gt45 turbo... since i got it on the road i feel its been way down on power...i was hoping for AT LEAST 500 hp it makes some torque not what i would expect but i was expecting a lot more up top and going down the road ive been pretty scatterbrained trying to check everything out at the same and im fried... my lastest discovery is that with my foot to the floor the car other reaches 4000 rpm it shoots a little above probably because of the inertia of the rotating assembly... obviously something is dropping out... any help is apprecciated