Ported Chevy 083 heads, the tpi project

[F-BIRD'88]

If you are not going to fill the crossovers completley right to the ex bowls at least fill them block them from cross talking bank to bank when running. EG: in the firing order cylinders 4 then 3 fire 90 deg apart... And then cylinders
#6 fires 90 deg from 3 and cyl 5 follows #6 90 deg later.
Sp at least block the connection beteeen the opposing cylinder banks.
I fill the crossovers by melting down old cast pistons and pore into the heat riser. When doing this I block the passage entrance in each exhaust bowl with a piece of curved formed sheet metal jammed in with a block of wood or a socket so it seals the entrance. Then grind the aluminum smoothin the bowl with a die grinder and rolls.

I think that stuffing the crossovers with balled up heavy duty thick aluminum foil should do just as good.
Cut up a thick aluminum catering cooking pan or tray.
Make big pieces and stuff them in tight in the passages.

I have not tried this yet.

[Kenny M]

Dynoed my engine today. I put a dual plane manifold and carb on it for the engine Dyno. When it goes in the car I will have it on the chassis Dyno to tune it with the TPI.
This engine is in a 1989 Five speed Blue Iroc. Numbers matching so I kept the 305. 334 CI now.It also has to pass California Smog. So it is a very mild build. 9.2 to 1, Crane smog roller cam 214 220 112 440 460 lift, Trickflow 175 heads. I have a ported edelbrock lower and SLP runners for the car. I thought I would share these numbers. I think this combo with the TPI will work great at 5500 rpms. I'm thinking I may loose 25hp but gain that in torque. Very happy with it. I was planning on it making around 330hp. P.S. Can't figure out how to adjust the photo,sorry..

334.JPG

[F-BIRD'88]

With my math it should run about @ or very close to 105 mph (1/4) with the carb.. Interesting to see the net effect of carb vs your TPI induction.
I get 326 hp net at the wheel..."observed"
See how close I get... (105 MPH 1/4) Will you be trying it out in the car with the carb induction?

I would have gone with much more agressive compression ratio unless yoyr local gas is of limited octane quality... You could supercharge it with 9.2:1 cr (add on later) You'd like that a Lot... especially intercooled w/EFI..

Are you verified on the CR measurement?
Its making good torque/cid for 9.2:1 cr.

[novadude]

I get that the exhaust will work better if they are filled as far as tuning but is it really worth the effort?

My guess is "no". Will the crossover be open at the manifold face? Wonder how that changes things when you have 4 ports (2 per head) connected at the bowl with all the associated waves, pressure changes, etc?

[Carnut1]

I get that the exhaust will work better if they are filled as far as tuning but is it really worth the effort?

My guess is "no". Will the crossover be open at the manifold face? Wonder how that changes things when you have 4 ports (2 per head) connected at the bowl with all the associated waves, pressure changes, etc?

It is an interesting question. Like having a 4 cylinder x pipe in the intake manifold.

[Kenny M]

With my math it should run about @ or very close to 105 mph (1/4) with the carb.. Interesting to see the net effect of carb vs your TPI induction.
I get 326 hp net at the wheel..."observed"
See how close I get... (105 MPH 1/4) Will you be trying it out in the car with the carb induction?

I would have gone with much more agressive compression ratio unless yoyr local gas is of limited octane quality... You could supercharge it with 9.2:1 cr (add on later) You'd like that a Lot... especially intercooled w/EFI..

Are you verified on the CR measurement?
Its making good torque/cid for 9.2:1 cr.

I just looked over my build sheet 9.43to1 measuring it correct including ring land. I run Junk California 87 fuel we are at $4.00 per gallon! I will not be testing the carb in the car. I am thinking around 280HP at the wheels with the TPI. With the small cam in at 110 it has 185 cranking PSI. I know that doesn't mean much, but around here that's my Max number to keep then from knocking with good timing.

[Kenny M]

Resized_20190321_184845_4233.jpeg Quick test of 48 mm t.b. with radiused tpi runners. This throttle body only loses 4.7cfm @ .5" lift over larger aftermarket (bbk) throttle body. So not much of a restriction there. It did come with an ugly center filler piece. It would be of interest to see how drivability and tip in are different with the two. Thanks, Charlie

I was just playing with mine on the bench. The trickflow 175 heads are on the engine. So i set a fully ported GM 186 head and set it to 235 cfm, that is what the 175 heads flowed. After fully porting the edelbrock lower with SLP Non siamese runners matched OEM upper and the stock 48mm Thottle body. Finished up at all cylinders 204CFM but Number 8 was 196. I closed the thottle plate about five percent this gave them a slight upword angle and it picked up to 206CFM. After some deep porting on the Number 8 plenum it picked up to 203CFM. I think this is plenty of airflow for my little 334 Cu
5500 RPM 384 hp Engine. Maybe i will get lucky and loose nothing over the carburetor.

[MadBill]

...Can't figure out how to adjust the photo,sorry..
334.JPG

To rotate the image 90° clockwise, put the cursor on the pic and left click.

Also, engines with four connected heat riser ports are widely reputed to gain significant power by plugging same.

[F-BIRD'88]

This could be A - B tested right on the dyno by removing the intake manifold and the headers for access to stuff the exhaust riser passages and ensure the material does not protrude into the exhaust bowls, using the balled up stripes of heavy gauge aluminum foil to block the 4 exh passages. The auminum need not be stuffed flush to the ex bowl. Just block the Y in each head to stop exh port cross talk.

[Carnut1]

Resized_20190321_184845_4233.jpeg Quick test of 48 mm t.b. with radiused tpi runners. This throttle body only loses 4.7cfm @ .5" lift over larger aftermarket (bbk) throttle body. So not much of a restriction there. It did come with an ugly center filler piece. It would be of interest to see how drivability and tip in are different with the two. Thanks, Charlie

I was just playing with mine on the bench. The trickflow 175 heads are on the engine. So i set a fully ported GM 186 head and set it to 235 cfm, that is what the 175 heads flowed. After fully porting the edelbrock lower with SLP Non siamese runners matched OEM upper and the stock 48mm Thottle body. Finished up at all cylinders 204CFM but Number 8 was 196. I closed the thottle plate about five percent this gave them a slight upword angle and it picked up to 206CFM. After some deep porting on the Number 8 plenum it picked up to 203CFM. I think this is plenty of airflow for my little 334 Cu
5500 RPM 384 hp Engine. Maybe i will get lucky and loose nothing over the carburetor.

It will be interesting how she does with the modded tpi. Which dual plane and what size carb did you use? Many dual planes have trouble flowing 220cfm through a carb and intake manifold. Thanks, Charlie

[Kenny M]

Professional Products Crosswind a super cheap copy of a RPM Performer Worst casting that I have ever seen . and a 4779.

[F-BIRD'88]

Professional Products Crosswind a super cheap copy of a RPM Performer Worst casting that I have ever seen . and a 4779.

My. Crosswind fit perfectly. Car ran 11's . cannot be that bad.

[Kenny M]

It fit fine just the casting looked like a old prototype mold. and the inside casting was super rough. I bought it only for the dyno test because it was cheap. The engine make much better power that I expected. So I am certainly not complaining.

[F-BIRD'88]

Funny, custom boutique manifold porters charge extra for that. "Burr finish". Hummm..

[econo racer]

Adding that 1/4 inch stroker crank was the best thing for that motor in your instance. What you did to the heads was a labor of love. And it worked out good too. I have done that before to a set of camel humps because it was what I had. Looks like a great combo. I say it will run 13.5 at 103 Also will get decent fuel mileage too.