con't turbo conversation on vj-23

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February-10th-2003 | 02:52 PM

#16

PinkMX-3

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Joined: Feb 2002

Posts: 87

From: Gainesville, FL

Quote:

Originally posted by turboge

We tuned Adam's GTX motor with a VJ-23 on it to 282whp @25psi. Which is in the efficiency range of the turbo and where the GTX head could flow no more. We tried it at 30psi and only gained torque.

Contrary to what you may think jesse the efficiency range of that turbo is 1.8bar which is 26.46psi. It has a maximum boost of 2.3bar which is 33.81psi.

Here is a comparison of the turbo's with a T28 also.

Gtir T28 Turbine 53mm
Compressor 60mm

Gt-R Vj23 Turbine 62.5mm
COmpressor 65mm

Gt-X Vj20 Turbine 52mm
Compressor 52mm

As you can see the GT-R is MUCH larger, and is about the size of a small T04.

A VJ-20 will max out its efficiency at 12psi. It will run 18psi till 3500rpm and drop slowly down towards 9-10psi by redline.

A GT-R turbo will run 30psi to 8000rpm as displayed on our dyno videos from adams web page. A link is available off of my site.

Due to the rarity of the GT-R turbo, if you can get one I'd recommend using it as a bolt on. If not, go with a small t3/t4 combo.

Also, this talk about streetability.. We ran adams car at 10psi on the street and had the boost controller setup at the turn of a ****, i set max boost to 25psi and we pulled up on a porsche and took off at 10psi, then i cranked the **** and screamed past him at 25. The turbo kicked into overdrive at 4000-4500rpm but spooled nicely at 2800.

The smallest T4 turbine wheel has a major diameter of 74.2mm, and the smallest T04E compressor has a major diameter of 74.93mm. A smidge bigger than a VJ23. Maybe that's why Ric is over 100whp ahead of you?

282whp at 25psi on a BP is hilarious, since the BP miata guys get those kind of numbers [with the less effecient RWD setup no less] around 16-18psi, with properly sized turbos, even with the conservative FM kits.

February-10th-2003 | 02:57 PM

#17

turboge

Goodbye everyone

Joined: Oct 2001

Posts: 383

Quote:

Originally posted by PseudoRealityX
Then explain why you're still over 100whp behind Ric's miata. :shrug:

8.2:1 Compression
No porting/polishing of the head.
Conservative tuning.

I didn't know ric was using a VJ-23 either Jesse.

February-10th-2003 | 03:09 PM

#18

turboge

Goodbye everyone

Joined: Oct 2001

Posts: 383

[QUOTE]Originally posted by PinkMX-3

Quote:

The smallest T4 turbine wheel has a major diameter of 74.2mm, and the smallest T04E compressor has a major diameter of 74.93mm. A smidge bigger than a VJ23. Maybe that's why Ric is over 100whp ahead of you?

Possibly, thats a lot more flow capable.

Quote:

282whp at 25psi on a BP is hilarious, since the BP miata guys get those kind of numbers [with the less effecient RWD setup no less] around 16-18psi, with properly sized turbos, even with the conservative FM kits.

Yes, I know, but we worked with what we had available. That is what the motor wanted to produce, I played with it for quite some time adjusting timing and making sure the A/F's were safe. I kept it rich above 20psi to make sure the motor didn't melt. The A/F is between 10.5-11.5 under boost there. At 10psi we could run it a bit leaner around 12.5.

I've tuned miata's with small T3's at 10psi and made 292rwhp. Then again, it was 10:1 CR, race head, cams, etc...

Remember this is a bone stock GTX motor, with a GT-R turbo bolted on and 550cc injectors. We were maxing them out as well. With a set of 720's, some headwork and some more tuning I'm sure theres more to gain on his car. But it still hauls *** and is very reliable.