Dual EGTs

[classicauto]

Barry, yes I moved from an FC greddy cast (collected, an majorly unequal runner length) to a-spec's FC manifold. It would be considered medium length IMO. Runners fully divided, length about 9".

The EGT's have gotten slightly lower on the setup. A decent back to back test was on the very same engine (basically stock port S5 TII) done minus the turbo change....

Using the cast with the aspec GT3574 .84 T4 housing, and same WI nozzle, EGT's could touch just over 1000C by redline. (@20psi)

Aspec manifold, T04-R 1.00 T4 housing and same WI nozzle, EGT's stay under 1000C (usually 975C highest) by redline.(@20psi) (also note, that this setup with larger turbine housing and turbo was as responsive as the old on the log type mani!!)

They have also stayed more equal during boost between front and rear with the new mani.

Exhaust on both setups was custom 3" piping from turbo splitting to dual 3" infront of the axle.

I've also thought of moving to 4" from the turbo down to the 3" split. Turblown has told me the extra volume is really helpful on a p-trim turbine (what my t04-R has)

I doubt I'll make that change this year though, because I'd like to be able to log EBP, and make the change on the dyno for a direct comparison.

[Barry Bordes]

Originally Posted by classicauto

Barry, yes I moved from an FC greddy cast (collected, an majorly unequal runner length) to a-spec's FC manifold. It would be considered medium length IMO. Runners fully divided, length about 9".

The EGT's have gotten slightly lower on the setup. A decent back to back test was on the very same engine (basically stock port S5 TII) done minus the turbo change....

Using the cast with the aspec GT3574 .84 T4 housing, and same WI nozzle, EGT's could touch just over 1000C by redline. (@20psi)

Aspec manifold, T04-R 1.00 T4 housing and same WI nozzle, EGT's stay under 1000C (usually 975C highest) by redline.(@20psi) (also note, that this setup with larger turbine housing and turbo was as responsive as the old on the log type mani!!)

They have also stayed more equal during boost between front and rear with the new mani.

Exhaust on both setups was custom 3" piping from turbo splitting to dual 3" infront of the axle.

I've also thought of moving to 4" from the turbo down to the 3" split. Turblown has told me the extra volume is really helpful on a p-trim turbine (what my t04-R has)

I doubt I'll make that change this year though, because I'd like to be able to log EBP, and make the change on the dyno for a direct comparison.

Classic,
It would be interesting to see your temps with larger AR turbine housings, say .96, 1.0, and 1.15.

I really think that our high EGT are a port overlap problem. The exhaust gases are contaminating the incoming charge causing a slower burn rate.

The solution then might be to redesign the exhaust port to slow gas reversion.

Barry