Built b16, hi comp + boost ??

[IEVAQ8]

Compressor efficiency has very little to do with engine RPM.... it's based on pressure ratio and air flow which comes down to the amount of power you wish to make

but with the efficiency range (air pressure) being not enough, u will notice it and feel it in the revs and how early the power will drop off,

the theory i have for building a honda, is very similar to building a rotary........
they love to rev (so do honda's) they responde exceptionally well to boost (as do hondas) and if tuned properly our hondas will last forever.....

dont be fooled with smaller turbos and too much lagg........

i think deanno said this once............

u cant really call it lag if the car was originally NA............the car will drive like it always did in NA form (off boost) and then u have boost............so its not really a down fall.......as the car wont and doesnt loose its charactaristics in the form of NA, just has the extra grunt with boost.

[Limbo]

The larger the turbo there will be lag.
The lag is the amount of time needed to produce enough puff to fill the turbo & piping.

As we have high comp & high revving the lag is generally reduced.

But your right, if your efficiency comes in too early you will out flow the turbo (happened to me also).
With the T28 it looks like at about 7krpm the turbo flattens abit. Only really noticable at 140km/hr

Also the T28/T30 generally is to indicate what flange you get.
There are your unusual ones which are T28s with T3 flange

[votek]

yeah but they are talking about lag in regards from a honda motor compared to sr20

[ZeForce]

Is the power dropping off in the higher rpms due to compressor efficiency or restriction in the exhaust housing? Generally, turbo "lag" is determined by the exhaust housing size. Smaller = quicker spool but will become restrictive in the high rpms. Larger = take longer to spool but with breathe better in higher rpm and hence make more power.

[Limbo]

yeah but they are talking about lag in regards from a honda motor compared to sr20

yep agree completely

[Limbo]

I think its restriction in housing in my case.

Is the power dropping off in the higher rpms due to compressor efficiency or restriction in the exhaust housing? Generally, turbo "lag" is determined by the exhaust housing size. Smaller = quicker spool but will become restrictive in the high rpms. Larger = take longer to spool but with breathe better in higher rpm and hence make more power.

[IEVAQ8]

Is the power dropping off in the higher rpms due to compressor efficiency or restriction in the exhaust housing? Generally, turbo "lag" is determined by the exhaust housing size. Smaller = quicker spool but will become restrictive in the high rpms. Larger = take longer to spool but with breathe better in higher rpm and hence make more power.

the only difference in the 2 setups is t28 rated at 400hp to gt3037s rated at 550hp cast log manifold - fullrace stainless tuned length manifold and 2.5inch exhasut to 3inch exhaust and internal 0.86rear housing to external 0.82 rear housing.............the power graph is the same and almost identical lag........

then u see the t28 drop off, where the gt30 love making power and revs

[Limbo]

do you mind me asking which t28 you had previously? Looks similar to my T28R setup,
The GT2876r is rated at 480hp same as the GT3071r
hopefully it will respond similarly to your GT3071

[ZeForce]

do you mind me asking which t28 you had previously? Looks similar to my T28R setup,
The GT2876r is rated at 480hp same as the GT3071r
hopefully it will respond similarly to your GT3071

What sort of power are you chasing?

[Limbo]

about the 180kw atw mark. Only need abit more power, just something to easily pull me into the 12s.

[Davo]

IEVAQ8, the 2 setups your comparing are quite different. Using and internally gated t28 turbo with a .86 rear housing, smaller exhaust and log manifold to a externally gated .82 rear housing 3037 with larger exhaust and tuned length manifold. naturally with a smaller rear housing, external gate setup and bigger exhaust and tuned manifold you would reduce lag considerably.


i originally had a GT28R on my 180sx. with the exact same setup and only changed the turbo to a 3071R with the same Comp housing and same .64AR t28 rear housing, the turbo was laggier (not by much) but yes it definately did make more power.

on both setup were you running the same amount of boost too??

[ZeForce]

IEVAQ8, the 2 setups your comparing are quite different. Using and internally gated t28 turbo with a .86 rear housing, smaller exhaust and log manifold to a externally gated .82 rear housing 3037 with larger exhaust and tuned length manifold. naturally with a smaller rear housing, external gate setup and bigger exhaust and tuned manifold you would reduce lag considerably.


i originally had a GT28R on my 180sx. with the exact same setup and only changed the turbo to a 3071R with the same Comp housing and same .64AR t28 rear housing, the turbo was laggier (not by much) but yes it definately did make more power.

on both setup were you running the same amount of boost too??

I would also like to point out that the 0.82 T3 exhaust housing is actually bigger than the 0.86 T28 exhaust housing.

Anyways, I crunched some numbers... 180kw@wheels is roughly 300hp@flywheel which would require a flow rate of 28lb/min @ 12-13psi for a B16a. If you wanna check these numbers yourself check the garrett website for the equations. I have graphed the compressor efficiency for 4000-8000rpm. As you can see the 2871R and 3071R are pretty close to the surge limit and would definitely experience surge with a smaller exhaust housing. However, peak power does fall in a much more efficient part of the map and hence will produce more power but IMO this isnt really ideal for a street setup but much better suited to a dyno queen.