Bolt-on Boss bb turbo vs GT35R?

[tekdeus]

Just wondering about the performance differences between a bolt-on turbo like the Boss/Comp 61mm turbos and a full T4 setup with a GT35R? I know a T4 manifold and external wastegate will have better flow and boost control, and probably have a better powerband, but how much of a difference is it really?

The ball-bearing Boss SS turbo with larger exhaust and compressor is extremely close in specs with a GT35R. It has a larger than stock wastegate, so the only real downsides I can see might be the turbulence of exhaust through the stock manifold and a CT26-style 3" downpipe. And I would plan to recirulate the wastgate flow which would just cause turbulence at the bottom of the downpipe, instead of at the top elbow. Not sure if that would make any difference.

 

[Nick M]

I think that is a good topic. Thanks for bringing it up. I will probably do the BOSS, not for the sleeper effect, but to maintain the vehicle as stock and stock appearing as possible. But that is just me.

Looking forward to good discussion.

 

[GrimJack]

Have the guys making the Boss units posted a flow map?

 

[tekdeus]

It seems that they are now made by Comp Turbo, by guys who were part of ITS which is now out of business.

 

[black91turbo]

hmmm i thought that the GT35 is a T3....no? Regardless I see your point..

 

[shaeff]

The GT35r can be had in a T4 footprint.

 

[frontierguy25]

I think that it just comes down to how much you want to spend and how much power you want to make. The turbos are about the same price, however with the GT35 you have to buy a new manifold, wastegate and downpipe. If your goal is 500rwhp at high boost then I say go with the Boss.

 

[upgradedsupra]

Mike (local guy) has the GT35R and putting down just under 450 @ 16PSI. I just called him and left a message to get some more info on his set-up. (he's not on the net)

Duane

 

[lintlars]

Ive been running my gt35r for three years now with a china manifold I run low boost on the street 11 psi Im so happy I went this route I love how a tubular manifold sounds! Im currently running 44 mm tial wastegate, got a 12.1 @ 124 mph out of it at 18 psi only got to put three runs down try again next year for 11s Im also running off the factory ECU with 550s,and the lex and an old rebic lc great setup for me I forgot to add im running a .68 T4 housing I purchased the turbo through kinetic in Van.they gave me a great price on it.

 

[Jack]

It seems that they are now made by Comp Turbo, by guys who were part of ITS which is now out of business.

The comp series and BOSS are to different turbos. The BOSS refers to the exhaust housing which we designed, cast and machine here in MN. Justin & Joe used to work for ITS and then started their own business called Comp.

I will post up some maps as soon as I get them

 

[SupraMan1987]

Any more maps on this? Any real info on what can be expected as far as lag and acceptable boost numbers witht he ball bearing boss? I'm looking into it. Could HKS intercooler and hard pipes be used?

 

[Toy-Rific]

Any more maps on this? Any real info on what can be expected as far as lag and acceptable boost numbers witht he ball bearing boss? I'm looking into it. Could HKS intercooler and hard pipes be used?

Call me 651-342-0100 and I will try to help you
Greg
Lipp/SS

 

[Justin727]

Good Topic. I too am interested!! Although I have a full T4 setup I was pondering the idea of the boss turbo's and have been for sometime. Wish there were more people running them with their larger wheels.

I would love to see the HP outputs of these and would love to see one break 600.
I thought about selling my current setup all new for a big boss bolt on. But no one has really gotten one and have posted large numbers 600+.

 

[Jack]

I can't fin d Malloy's dyno vid anymore made by MK3Brent. I cannot remember what he ended up with but I am pretty sure it was over 500 on stock manifold. I will keep digging through files to find his info.....

 

[Justin727]

yes I remember his vids very clearly!

But has anyone been able to dyno with the largest boss yet?

 

[frontierguy25]

On 26psi he made 556 or something like that with the Boss He had

 

[Toy-Rific]

yes I remember his vids very clearly!

But has anyone been able to dyno with the largest boss yet?

The largest turbo I have built is one with an X trim and a 74 compressor wheel in a GTS cover. The car is still being built and it has not been on a dyno, should be 850 hp on the stock manifold. I am waiting to see just what the car and the stock manifold will do.
The "largest" as you ask is a very responsive set up. It is a P trim with the 67 compressor wheel. It is sold mostly in triple ceramic ball bearing and has the GTS cover. The GTS cover has a 4" intake with 2 1/2 outlet. This is rated 685 hp.
When you get in to the 550 hp and up your car must be built to be able to pull the power out and than built to control the power to the ground. This takes a lot of money to do this. This is one reason that most are in the 450 to 500 hp range and don't need the largest turbo out there, lots of money.
I do have this turbo on the shelf and if you would like to put it on your car and dyno it, e-mail jack@suprasport.com and he will work with you.
No one that have this set up has given me any dyno slips, they build them to drive and not thinking about dyno numbers. There have been over 3 dozen of the P trim set up and not one complaint. Yes about 36 turbo's is not a large number, but how many people do you know are pushing a true 600 plus Mark III

 

[Justin727]

right, but I dont think he had the largest boss turbo made...Refering to malloy's setup

 

[shaeff]

Not exactly sure why you'd want to push 850hp using a stock exhaust manifold... If you're spending that kind of money (supporting mods), just get a tubular manifold...

 

[Justin727]

although it may seem like a waste to us.

I would be curious to see how well the stocker and how much boost he would be using to break 600 ot atleast 700.