6 replies to this topic

[coopa]

Just wondering about flowing the head of the Ecotec engine. This has been part of Stage 3 tunes for various firms, but does it actually make any difference for the RPM range of a street/track day car?

I found this post on the ecotecpower forum in response to a guy who was getting a cylinder head ported:

you can't look at it and say it flows better.... a few differt companies have messed with porting the ecotec head and gave up because its hard to get gains out of the head, not worth the time/cost. Simply saying "He is about half done and you can see a clear improvement" doesn't mean anythign since you can't see flow. A head can flow a million CFM but if its not at a usable range then its worthless, plus hand porting means different results everytime.

Does anybody have flow bench data for the standard head, and also results after the head was ported, for a range of valve lifts? This may help quantify this a little bit.

Edit to say: Yes, the title should read L850 head

Edited by coopa, 24 May 2006 - 11:36 AM.

[clipping_point]

I think it is obvious that u need the porting if you want power exceeding 180 hp, from the figures I´ve seen. This means porting seems to work! Also there are several bottlenecks that can be evened out. A drawback with larger channels may be lower gas velocities on low revs. I don´t have any test results tho...

[vocky]

the standard z22se ports do have some restriction, mainly the throat area most cylinder heads are mass produced for cheapness and not produced for performance gains I would attach a picture of a head half ported to show the improvement, but still no upload

[coopa]

Granted the stock ports do look rubbish:



and a lot better when ported:



but unless there is some measure of improvement then why bother?

If you need gas flowing to go past 180 bhp, and I assume this would mean an increase in the rev limit (?), then as part of the Stage 3 tune (170 - 175 bhp max according to TMS site, which may be optimistic given recent RR results), it probably isn't worth it?

[2-20]

Some figures on a ported head

HERE

and perhaps HERE for stock ones

[coopa]

Some figures on a ported head

HERE

and perhaps HERE for stock ones

Top man, thank-you

[coopa]

Ok just for giggles I've done a comparison of 3 cylinder heads: Ecotec (ours), 350 Chevy (responds very well to head porting) and VW Golf 1.6 (hardly responds to head porting).#

Lift in inches, flow in cubic feet per min.

Ecotec:


Chevy:


Golf:


so the Ecotec would seem to be somewhere in the middle.

One thing to bear in mind I suppose is that the ported figures for the Ecotec came from a website where a company is trying to sell they're product, so will be the best figures they ever acheived (maybe with a bit added on for luck).

The other figures I've nicked from a book on engine tuning, so are probably more realistic

Edited by coopa, 24 May 2006 - 01:19 PM.