Dyno Test: Mod Progression

[1990 quasar blue]

Originally Posted by gbmidyear66

I am hoping to break 380 with Intake, Plenum and TB porting I currently have in process. Will post Dyno results when this winter's project is complete

That would be great and those mods should get you another 30 or so hp. I'm currently at 378 rwhp with previously mentioned mods plus headers. I'm actually about to order the ostrich from moates, so maybe I can find a few more in the tune.

[Paul Workman]

Some pix of work in progress, just to give you an idea...

The porting begins with a plan; it may be a copy of a successful model, or a new pioneering adventure. The point is, there is considerably more to it than making holes bigger. LT5 parts are expensive. So, unless you have experience with porting and have a basic appreciation for the principles at work, then sending it out to someone that does have a model will probably be cheaper and results predictable in the end.

I say this, because these pix of my setup may or may not be representative of what your's might look like, depending on the application - or it might be similar if you send it to IL for one of the FBI gang to do for you (recommended). I'm just saying...Mine may not look like yours or anyone elses. KThat said...

...this is a 90 IH. Notice the primary runner looks fairly clean. The injector buss is completely removed (the primary injector on the 90 is sealed at the top of the injector). What remains in the secondary runner is a nub of what was a rather large intrusion; the boss containing the seal for the secondary injector gasket.



In this picture you're looking down the IH at the head transition.



Here we see the head port matching in progress with the head in place. The ball gauge is a steel ball held by one of those magnetic wands. A plastic shower curtain is laid over the entire engine bay to keep chips etc from getting where they shouldn't be - like an operating room in a hospital!



I'll let you in on a little secret: Some only port match a short distance down into the head on the primary side. And, some don't even touch the secondary side of the head as it is already 36mm across. BIG (hp) mistake!

If you taper the port from the top of the head down nearly to the valve guide, then the shape of the runner will conform to good engineering practice as far as avoiding sudden changes in the passage diameter...if you get my drift. It WILL be worth the effort...as long as you don't stray off the line and get into the water or (worse) oil cavities.



A picture of the top of the head after the heads were fully ported.



Some feel removing the secondaries will not affect hp to any significant degree. Well, laminar flow dynamics says the highest velocity in the column will be in the center of the air column. How much hp is gained by removing them? I wish I could say. However, them being there flies in the face optimum flow dynamics principles. I removed mine. 400 RWHP is possible with plenum and IH porting, with proper head port matching, in conjuction with headers and a tune. Over 30 more RWHP is possible with full porting and cam timing.

Well, not a lot of detailed info. But, you get an idea of the symetry anyway.



P.

[Bob Eyres]

I'm with Pete on the concept of trap speed as a great indicator of actual hp applied to the road, (strip), as e.t. is useless in this regard.
Although my only dyno runs (stock) with my car cranked out only 326 whp. With a good intake ("forced air"), and free flowing exhaust listed below, it actually trapped over 117mph. in the qtr, on a humid Florida night at over 80F. That's 7mph. more than it was able to do bone stock.
If I ever make the leap to all the top end mods, I could only hope to be in that 550+chp. territory. That's phenominal for a naturally aspirated, stock block,350 Chevy.
LT5's rule, and they "don't need no stinkin' blowers".