[SupraPL]

Hi guys.

I'm Supra MKIV owner.

Now as a personal preference i prefer faster response and lower top speed. So i'm looking for a turbo with the least lag [broadest torque curve] i can get and still get 450hp at crank (375whp).

I can't decide between two turbo's [GT-K 450 vs GT-K 500] and i want to know what you guys think.

Which turbocharger will be better for my goal (450bhp at crank)?

Kind regards
Tomasz

[Robert]

I would go with the GT-K 500 personally and voted as such. The 2JZ motor has such potential that I don't think the T04E 60 trim compressor on the GT-K 450 is well suited for it. The GT-K 500 uses a 61mm GTK61 compressor wheel. Its essentially a redesigned version of the 60-1/62-1 compressor wheel. That would be my first choice. The turbine sections are identical between the GT-K 500 and GT-K 450 anyways...

[SupraPL]

Originally Posted by Robert

The 2JZ motor has such potential that I don't think the T04E 60 trim compressor on the GT-K 450 is well suited for it.

Why do you think so?

[Robert]

Originally Posted by SupraPL

Why do you think so?

The peak flow for the T04E 60 trim is about 50 lb/min. The peak flow of a GT-K 61 compressor wheel is over 57 lb/min and both units will spool up almost identically. That fact alone would lead me to use the GT-K 500. It has a lot more head room than the GT-K 450 with almost the exact same spool characteristics. It's even using the exact same turbine section. Only difference is compressor wheel and cover.

[SupraPL]

Originally Posted by Robert

The peak flow for the T04E 60 trim is about 50 lb/min. The peak flow of a GT-K 61 compressor wheel is over 57 lb/min and both units will spool up almost identically. That fact alone would lead me to use the GT-K 500. It has a lot more head room than the GT-K 450 with almost the exact same spool characteristics. It's even using the exact same turbine section. Only difference is compressor wheel and cover.

Thanks for reply. Where can i find compressor and turbine maps?

[Robert]

Originally Posted by SupraPL

Thanks for reply. Where can i find compressor and turbine maps?

The compressor map for a T04E 60 trim can be found here: http://www.turboneticsownersclub.com/viewtopic.php?t=17

I don't have a compressor map for the GTK61 compressor wheel unfortunately nor do I have a turbine map. As I said both the GT-K 450 and GT-K 500 use the exact same F1 T3 Stage 3 turbine wheel with the exact same A/R. The only difference between the two units is the compressor wheel and cover.

[Talonboost]

I voted GT-K 500 also. The turbine wheel and housing have more effect on spool than the compressor does, so I don't think you would have much if anything to gain spool-wise by using the 450 instead of the 500. But I bet either one would make your hp goal. You aren't going to need very high boost pressure to make 450hp at the crank with that 3 liter engine.

The GT3076R would probably be fine also, but I wouldn't go with any of the larger Garretts, especially not the GT35. Not if you want killer spool.

[SupraPL]

What do you think guys about HKS GT3037 Pro S 56T and HKS GT3037S 56T?

[Talonboost]

[quote]What do you think guys about HKS GT3037 Pro S 56T and HKS GT3037S 56T?[/quote

The HKS GT3037 turbos are Garrett GT3076 as far as I know. I've never seen a really good description of what the differences are between them, if any. Well price, the HKS's are pretty expensive. I wouldn't pay for one unless somebody could prove to me that they are worth the extra dough over a regular Garrett.

Speaking of price, I've noticed the prices on the GT-K's have come down - especially the GT-K 450 and smaller. Check out the prices at AGPturbo.com.

Here's a wild idea if you want spool: How about some kind of a 50-trim turbo? I mean a T3/T4 with TO4E 50 trim compressor and ball bearings. There are lots of people around getting 375 whp with 50 trims. You would have to be more liberal with the supporting mods because the 50 trim is near maxed out at this level if you are talking 375whp on pump gas. But even if you missed your hp target by 5 or 10 you'd make up for it with wicked spool and fat torque at low revs. The GT-K 350 uses a TO4E 50 trim compressor so that would be one way to go. Most of the guys making big hp with the older 50 trims are using the stage 3 turbine wheel. The GT-K 350 uses a new turbine wheel that I bet would spool quicker than the old stage 3. I don't know if the hp potential at top end would be as good but it's probably close. One thing cool about starting out with a smaller turbo like this is that even if your supporting mods aren't quite up to snuff at first you will still get great spool and solid overall performance - it'll be fun to drive! Then as you get better supporting mods your top end hp will go up without losing the good spool.

[Robert]

I would still opt for the GT-K 500 personally. We all know that are targets on boost start small and just get bigger over time. The GT-K 450 and GT-K 500 both use a F1 T3 Stage 3 turbine. Not only is the spool up better but it actually flows better than a standard T3 Stage 3 so you sacrifice nothing in the top end. The beauty of the GT-K 500 over the 450 is the 61mm compressor. Spool up wise they will be nearly identical in the end and with the GT-K 500 you'll have soooo much more head room than you would with a T04E 50 or 60 trim compressor.