Why doesn't A/R matter ?

[a1091156]

Since I can't post in the relevant thread, hopefully someone here can post this question in there for me

http://www.dsmtuners.com/forums/showthread.php?t=192083

That's right, why do people not seem too worried about running 60+lbs of air through a 0.49 A/R Exhuast Housing.............just for the simplicity of being a Bolt-on thing.......?

If you guys are serious about chasing big numbers, why take shortcuts ?

Unfortunately for the life of me, I just can't figure it out........if you really wish to save $$$ that's your choice but when there are HRC 25G Turbo's with 0.89A/R going for only $900 new with Internal Wastegates (which btw doesn't mean you lose power) and is rebuildable compared to the GT##R Turbo's, I don't see what the fuss is all about.......can you imagine how much back-pressure would be going through that tiny housing even just running it at 15psi ? Isn't it common knowledge that back-pressure robs power ?

That's my rant for the day.....if you want to run the Holset Turbo, do it with the matching Holset Exhaust Housing otherwise your wasting your time and money......care to prove me wrong ?

I'll see how long it takes for the big boys from the other thread to come on over...

 

[vr6chris]

I agree, there is no reason to run a housing that small. Smallest I would every go would be a .68AR. I ran a .96AR on my t4 60-1 and on my GT40 turbo, i ran a .81AR. The smaller housing definately helps with spool up, but robs the top end of power.

 

[ddavisaf]

Personally I feel it all depends on your setup. If you're running 1/8 mi tracks, then the smaller exhaust housing will be beneficial as opposed to something that lags more. Autocross I would go with a smaller housing as well, but for a nice 1/4 mi drag bigger would be better.

 

[a1091156]

That is correct, but posting up HP figures or dyno graphs leads me to believe otherwise

And even so, there is a point were the A/R is so small that it just results in uncontrolable wheelspin and slower 60ft times, even if 4WD.......

 

[GILZTSIAWD]

Since I can't post in the relevant thread, hopefully someone here can post this question in there for me

http://www.dsmtuners.com/forums/showthread.php?t=192083

That's right, why do people not seem too worried about running 60+lbs of air through a 0.49 A/R Exhuast Housing.............just for the simplicity of being a Bolt-on thing.......?

If you guys are serious about chasing big numbers, why take shortcuts ?

Unfortunately for the life of me, I just can't figure it out........if you really wish to save $$$ that's your choice but when there are HRC 25G Turbo's with 0.89A/R going for only $900 new with Internal Wastegates (which btw doesn't mean you lose power) and is rebuildable compared to the GT##R Turbo's, I don't see what the fuss is all about.......can you imagine how much back-pressure would be going through that tiny housing even just running it at 15psi ? Isn't it common knowledge that back-pressure robs power ?

That's my rant for the day.....if you want to run the Holset Turbo, do it with the matching Holset Exhaust Housing otherwise your wasting your time and money......care to prove me wrong ?

I'll see how long it takes for the big boys from the other thread to come on over...

Do you realize how long it would take to spool a turbo with a .89 a/r on our 2.0 liter cars? Also back-pressure in the exhaust robs power, turbo cars actually need to have backpressure from the turbo.

 

[GILZTSIAWD]

eh, just saw that you live in Australia. That is one beautiful place!!! Wish I lived there! I went and visited over there in Melbourne, Sydney, Brisbane, Cairns, etc. Got to go there for 21 days and didn't want to go home at all!

 

[a1091156]

What are camshafts for then ?

Yes I know it does take a bit to spool, but I assumed 6K dial up's on the 'stutter box' was more then enough to handle it

 

[a1091156]

eh, just saw that you live in Australia. That is one beautiful place!!! Wish I lived there! I went and visited over there in Melbourne, Sydney, Brisbane, Cairns, etc. Got to go there for 21 days and didn't want to go home at all!

I betcha the girls over here did it for you ?

 

[GILZTSIAWD]

I betcha the girls over here did it for you ?

Oh yeah...they were great!!!

You could also get that size turbo to spool good with a little nitrous, but you would have to be running some nice internals to handle all the power. Granted if you are going for big power then yeah you want to go with a turbo of this magnitude. For most people on this board that is way overkill though and they just want to go with a big enough turbo to get them to their goals. Most people on this board are also worried about driveability on the road and they despise turbo lag. Personally I don't mind turbo lag a bit as I love the rewards that come afterwards! I would much rather pull like a freight train after 4500 rpms or so than pull mediocre from 3200 up! Its all in the preference of the user and what the user wants, but most good times are going to come from something that provides spool up alot quicker that 6k rpms, as without revving the engine way higher than it really should be on a regular basis you are not going to stay in this size turbos range.

 

[spoolinawd91]

I wouldn't say that the housings are all to small. I mean a holset hx35/40 hybrid spools 20psi by 4500 and a HX40 spools 21psi by 4800-4900 with these housings. Now these turbo's won't be able to make there max power but enough of it for most people. With that said I would think the a/r on the turbine would be a little bigger than .49

 

[a1091156]

These Bullseye Exhaust Housings are just custom MHI 070 Casts for Garret Turbo's no ?......therefore 0.49 A/R

 

[GILZTSIAWD]

.60 in the v-trim and .58 in the p-trim i believe, so many different combos though...

 

[liquordrunk]

I'm still not sure what the FPRED is?

 

[Slippi84]

The fact that our low balling these exhaust housings power potential like they're a t25 or something is not the point. What is though is that those smaller housings from bullseye are DSM compatible. IN other words I don't have to go out and spend 300 dollars on a descent manifold and another 200 and somethin on a downpipe setup just to work on my car. I can take that 500 dollars and go buy an intake manifold and make up for that lost flow at the turbo and have a better overall car. I agree with the fact that flowing lots of air hrew a small housing is dumb but you have to put everything in prospective most guys getting these turbos aren't lookin to run 9's most are more than happy with low 11's sometimes higher depending on the individual. These turbos with Bullseye housing can easily produc3 450-500 awhp or around 500-525 whp. That is plenty to get the previously stated goals. Bigger is not always better. I have seen plenty bolt on t4's run slower times than the turbo they replaced you have to look at everything in prospective

 

[a1091156]

hmm, so does anyone know for certain what A/R are obtainable from these Bullseye Housings ?

0.60 isn't so bad.....

 

[suicidal2af]

Since I can't post in the relevant thread, hopefully someone here can post this question in there for me

http://www.dsmtuners.com/forums/showthread.php?t=192083

That's right, why do people not seem too worried about running 60+lbs of air through a 0.49 A/R Exhuast Housing.............just for the simplicity of being a Bolt-on thing.......?

If you guys are serious about chasing big numbers, why take shortcuts ?

Unfortunately for the life of me, I just can't figure it out........if you really wish to save $$$ that's your choice but when there are HRC 25G Turbo's with 0.89A/R going for only $900 new with Internal Wastegates (which btw doesn't mean you lose power) and is rebuildable compared to the GT##R Turbo's, I don't see what the fuss is all about.......can you imagine how much back-pressure would be going through that tiny housing even just running it at 15psi ? Isn't it common knowledge that back-pressure robs power ?

That's my rant for the day.....if you want to run the Holset Turbo, do it with the matching Holset Exhaust Housing otherwise your wasting your time and money......care to prove me wrong ?

I'll see how long it takes for the big boys from the other thread to come on over...

Some of us like daily drivability, too. It kind of sucks having to rev to 7 grand to pass someone.

Plus, not all driving is in a straight line. Broader powerband = better track times.