What is the stock runner size on my L98 heads? Also, the combustion chambers are 64 cc right?

So for a streetable, torquey engine I don't want to exceed 195 cc ports for aftermarket heads? Will I be o.k. with the Trick Flow 23 degree 195 cc heads? I wish they made them in 180 cc though.

When things are rated in HP and Torqe figures at the fly, how do you roughly calculate what they are at the wheels? I was thinking it was a 20% loss for an AT trans...let me know if I am right. Thanks

 

I think it's closer to a 30%-35% parasitic loss with stock drivetrain by the time you get to the rear wheels.

 

An engine that is rated at a certain gross flywheel brake horsepower figure is tested in a stripped down condition
and corrected to sea level air pressure low 60degF temperture and dry air. The peak power figure is usually obtained at a steady state rpm test which gives the highest figure. (no inertial to overcome)
The engine in your car never operates under these conditions. The air inlet temperture is usually higher more humid and at a different and variing pressure ( density).
The exhaust system is not the same as on a dyno.

All this trims the actual power the engine will make
at the flywheel, in your car.
Then, the driveline absorbs power (friction) reducing the net power at the wheels.
Then the inertia of all the rotating parts must be over come as the whole drivetrain accelerates from low speed to high speed. This inertia power absorbtion is independent of friction.
What you're left with is net horsepower at the wheels.
If, you actually get 75 to 83% at the rear wheels of what you'd get on a engine dyno, all said and done, that is about par for the course.
80% is a good ball park figure to use.

The better your "as installed" in car air temp/pressure/flow management, exhaust system performance and drivetrain friction design
the more power you'll put to the road.

 

Hey, thanks for the explanation. Does anyone have the answeres for my cylinder head questions? Thanks

 

Stock L-98 heads have 157cc intake ports ( approx)
the aluminum versions are 163cc.

All in all the TFS 23 deg heads are still a very torquey head even at 195cc's. Overall you'll be way ahead of the game both in turns of HP and torque. (because they just flow a lot more air.)
if you'd be more comfortable with a smaller port then maybe a Edelbrock Performer ( heat riser) or Performer
RPM head would suite you better. (170cc port)
(lots of flow and snappy 170cc high volocity ports)
they work well.

 

I've basically been look at the TFs and the Edelbrocks. Both heads are way different as for the size of the runners/chambers. I am planning on keeping my stock TPI setup, so I don't need a set of heads with huge runners, I want to keep it torquey for the street. So would the performer heads be better? They are smog legal and have the EGR port right? I'm not sure about those Performer RPM heads though.

 

Yes the Performer is smog legal. If you're going to use a stock TPI system then the smaller edelbrock 170cc port may be better. There is even a centerbolt version.
The RPM head is the same basic head without the Exhaust passage for EGR.

Consult the Edelbrock catalog. www.edelbrock.com.

A nice improvement over the stock head.

 

That's what I was thinking. I just hat to spend that kinda cash on the edelbrocks (about same $ for TFs) when they are almost the same size as stock! I'd hate to not get that much out of them over the stock L98 heads. Other than the fact that they are aluminum of course. Those performer heads actually have 165cc intake runners, and 60cc combustion chambers. And looking at the flow numbers for the TFs and Edelbrocks, the TFs are way better. So I don't know which is better.

 

I see AFR has 180cc heads for SBC's now...I think they go for around 1250 or so.

Just thought I'd confuse your mind a little more

 

Irocster: you're getting all wishy washy on me.

Yes a larger port will flow more air. But its only as good as the worst part. A larger port has less volocity and will want more rpm than a smaller port.

a large port bolted onto a small manifold is a mismatch.

the edlebrocks flow a lot more air than a stock head.
even at 165cc's. Check the flow numbers. Nothing stopping you from tweeking the ports yourself either if you want more flow.

It will make more power.

You need to trash the stock TPI manifold and runners the manifold and runners are the problem they are very restrictive and tuned for low-mid rpm.

its a pretty induction system to look at but the performance potential is limited by its internal size and runner tuning.

pro topline 23deg heads flow tons of air too. 165-180-200-220-230 cc ports available.

www.protopline.com

 

Sorry buddy, it aint easy trying to put a motor together I guess. This has got to get done by this summer, cuz the old 203,000 mile motor has got to go. I was looking into the protoplines and thought the flow numbers looked good, but then I read everywhere on here how they false advertise and all those numbers are incorrect. I am sure the AFRs are the best, but they are out of my price range, and I've read they take forever to get them to you. So that leaves me with TF (change over to better manifold/runners) or Edelbrock (stock manifold/runners). O.K., I got a (stupid) question....Since the runners on the edelbrocks (and TFs) are larger than those of the stock heads, will I need to open up the ports on the manifold to match it all up? Where can I get something like this done?

I would like to give porting my stock heads a try but once the motor is out of the car getting re-built, once it is done, it has to go right back in....no time to port heads.