Traded FP my life savings for a gt4205hta. Searching for spool times on a 2.0L and can't seem to nail down a number. I get anywhere from 5,700 to 7,100...

My setup is a JM Fab top mount v band manifold, Tial 1.16 A/R turbine housing. Journal bearing gt42 center section and turbine wheel.

Motor is a rebuilt stock 6 bolt. Only aftermarket parts are ACL bearings, arp hardware throughout, Manley single springs, HKS 264/272 cams. Stock intake and TB. Link v3 on SD for EMS. Car was built around the 68hta setup, hence the small cams and spring choice.

Car is a fwd 5 speed. (92 tsi). It's not in my profile, because.. Well I'm lazy.

Car was previously on a 68hta. I'm not looking for build/tuning advice. Just spool numbers a little closer then the range I've found via searching..

Have you asked FP?

Yes. They told me "There are to many variables to give you a better answer then you have found. 5,500 to 7,000 is the ball park. Tune, altitude, load, dyno type, gear used, tire size, weather conditions, etc. there are simply too many inevitables to give you a more specific range."

I've found these posts here on tuners (see attachments)..

I only plan to run in the mid 20 psi range. Which would slow spool from what I've read. I'm gather parts to have an built motor assembled next spring. Horsepower numbers aren't important on this setup. Just curious. I'd also like to keep my rev limiter as low as possible with my current valve springs, while still being able to use the turbo..

Buddy of mine's old cast 42R got it in by 6,000 rpm. He wasn't in a v-band housing though.



Question, and I'm not judging just honestly curious, why spend all that money on the 42R/V-band setup, before beefing up everything first and going slightly larger than the 68HTA?

I owned the gt4205hta long before (2 years almost), I bought the 68hta. I just never used it.

Well hell, I'm with you then. Have turbo, will use.


Honestly, how well do the v-band housings work as far as spool/flow? From what I hear they aren't as laggy as a traditional open T3 or T4 housing would be, but flow really well. Gotta keep us updated with some spool numbers that you find out. Sorry I couldn't be more help.

I'm not entirely sure how the Tial housing effects spool or back pressure. If there are any shops, or individuals, that know this info, they haven't shared it publicly. In there defense, a setup like this ($4,000+), not a lot of people can afford it.

My dyno numbers will be an odd combination of very opposing factors. FWD 5 speed isn't exactly ideal for a 42r street car. The cams are very small, and will definitely not be of much use where the turbo makes power. 20 psi isn't anywhere near the intended range of a 4205 hta. The last (and worst) part is I'm using a rebuilt stock motor (non ported head, cast pistons) and springs designed as basically stock replacements.. I'm going to say 350whp is a realistic dyno number.

The engine is currently at the machine shop. It'll be probably 2 - 3 weeks until they are finished with it. I'm not sure if I'll make it to the dyno before the years out. Sadly, the car is pretty far apart right now..

Why in the heck would you purchase a turbo made for ALOT more power and airflow than what your power goals are on a STOCK MOTOR??? 20ish psi, you will be lucky to hit your target boost pressures around 6500-7500rpm. Don't expect to put down 600-700FWHP either.

You could have gone significantly smaller for a turbo and make 600-700FWHP at relatively low boost pressures while having a much quicker spoolup and way better average powerband.

Heck, my low compression 2.3L on a similar sized turbo/housing makes 30psi around 6300 in 3rd when AWD, and around 6800rpm in FWD. It makes 20psi about 500-600rpm faster. On a 2.3L.

Tim, his motor has 98k miles on it (and was originally built back in 2006/07 when EVO III 16g's where "the turbo"). I'm building an AWD auto car with built motor and trans that this turbo will be on. This motor (stock rebuild), is just getting a refresh (bearings, hone, rings, checked out). I had a 68hta on the car (which was a perfect match with these cams, springs, etc.), but I traded the 68hta for the AWD auto roller, and don't have a turbo to put on. Hence the reason behind using the 4205 hta on a stock motor.

The 4205 hta wont be on this car for long (next spring more then likely), but I need the car to be mobile, and it'll get the bumper exit exhaust and lower intercooler pipe fabrication done. I understand I'm going a little backwards, but.. I bought this turbo 2 years ago and it's just sitting. I'm on the hunt for a regular 16g to put back on this stock motored FWD car in the spring before it gets sold..

go buy a used 16G then. it is completely backwards.

Put it on. It's still going to be a tire eater no matter how laggy it is.

Thats crazy. For a street car especially. My 6466 isnt hitting 38psi u til 6700 and it's in a 1.15 twin scroll and my tirbine is only a 66mm inducer. I find it terrable. I can imagine a 42r to be much worse it's kind of a drag turbo not a street turbo. I'd get a 16g like tim said or a 35r going from a 68hta to a 45r is... A little crazy

I was afraid that it wouldn't make boost post 7K, which isn't going to be a problem with the built motor in the awd auto car, but for the FWD car with the motor setup for the 68hta I don't feel like having an 8K rev limiter is going to work out so well. I guess I'll just keep this updated when get the engine back from the machine shop..

Test fitting on a mock up motor revealed the first (of many I'm sure), fitment issues. Wastegate (Tial MV-R), dumps directly onto the front subframe cross bar. Compressor cover touches the top radiator hose outlet. Zero room to run puller fans. I love a challenge!

90laserRSfwd said:

Test fitting on a mock up motor revealed the first (of many I'm sure), fitment issues. Wastegate (Tial MV-R), dumps directly onto the front subframe cross bar. Compressor cover touches the top radiator hose outlet. Zero room to run puller fans. I love a challenge!

Click to expand...

That is why people use top mount manifolds. Your gate can be routed to avoid your sub frame via the dump tube, radiator hose you may need AN fittings. And you will def need pusher fans and an mk3 golf radiator will help with spce. I jist went through all of this.

I'm not complaining. I'm running a JM Fab v band top mount. I'm looking into different radiators currently. Probably gonna run a custom Ron Davis half rad. He builds a nice setup for the sprint cars that'll fit right in a 1g with a simple tab mounting setup.

Nice manifold for sure. I had a half rad and it didn't work with my top mount. Thats why i went to the mk3 golf that is mounted in the rad support.

Are you running a v band turbine housing?

I don't wanna front half the car, or even cut the rad support. There's enough airflow from the turbo that boost will easily make up for the weight savings. A buddy has asked me if I'd be interested in having the car caged to 25.1 cert (8.50 ET), but I'd honestly like a street car at this point, now the other car (AWD auto Laser) is a different story..

Fast forward 3 months:

What's the latest?

, it will have a power curve like a Honda. I would just trade the whole setup to someone for a known good setup that's better suited for what you are doing on a stock block, maybe plus cash.

Cylinder head is back from the machine shop, bottom end turned out to be in much worse shape then we thought. The key way pin in the crank was worn so badly it wobbled around. So I either need to find another crank or have this one welded. Another issue, 3 of the 4 cylinders are going to have .006" piston to wall clearance and should really be .020 over'd. So... Looks like it would be a lot easier to just order a set of Wiseco's and Turbo Tuff I Beams at this point. We'll see how the cash flow is in the up coming weeks.