Help me choose twins for my 7M

[Kristian_Wraae]

I'm going to twin turbo my 7MGTE.

And before you say it's not worth it, I say it is.

End of discussion.

I've got a HKS twin turbo T25 manifold here.

So I'll be looking for a set of T25/T28 turbos.

My power goals are somewhat modest. Around 450 rwhp. I'd rather have less lag and faster spool and better power delivery curve than max hp. I'm going to drive this car and (hopefully) not park it sideways in the nearest lamp post.....

I'm of course going for ball bearing turbos.

Can you recommend something?

[A-to-the-J]

I'm going to twin turbo my 7MGTE.

And before you say it's not worth it, I say it is.

End of discussion.

I've got a HKS twin turbo T25 manifold here.

So I'll be looking for a set of T25/T28 turbos.

My power goals are somewhat modest. Around 450 rwhp. I'd rather have less lag and faster spool and better power delivery curve than max hp. I'm going to drive this car and (hopefully) not park it sideways in the nearest lamp post.....

I'm of course going for ball bearing turbos.

Can you recommend something?

how about twin HKS T51R SPL's? that would be SWEET ;) (sorry, I'm in a happy mood. LoL)

on a serious note, I would think something similar to the HKS twins they make for the 1J would be nice. They were very responsive and provided great numbers for my buddy.

[Kristian_Wraae]

Which turbos would that be? What is the equivalent Garrett models?

[A-to-the-J]

pm soapra aka Jose Valle about it. He was the one running the 1J HKS Twins...

They are gt25XX . The original HKS power potential was of 500ps to 550ps.

http://img.photobucket.com/albums/v150/onebad7m/hksclip010.jpg

[Kristian_Wraae]

So it'll be something like these: http://cgi.ebay.com/ebaymotors/Garrett-GT2554-GT2554-Turbo-Turbocharger-64-A-R-T25_W0QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247QQcategoryZ33730QQihZ013QQitemZ230272338053QQrdZ1QQsspagenameZWD1V

It says good for 170-270 hp.

As a rule of thumb, can you just multiply by 2 if you run two turbos?

[foreverpsycotic]

Twin gt28r turbos would be sick, take a look at BIC's thread when he ran them.

[figgie]

Twin GT28r?

That is a pretty significant sized turbo when only running 1.5L through each.

450 rwhp out of a twin turbo....at the biggest, 2x GT25 based turbo. That should net you roughly about 500 crank ponies.



My power goals are somewhat modest. Around 450 rwhp. I'd rather have less lag and faster spool and better power delivery curve than max hp

sorry Kritian

physics don't work that way.

If you run a parallel setup with 3 cylinders pushing one turbo. You are no cutting the displacement by half (1.5L per turbo). Lag will still be there. That is the nature of turbos. If you do a single gt25 or gt28. Lag will be minimal but you will outflow the turbo on the high end.

If you do a serial setup like the tractor pullers. Well now you are pushing the turbos with the full 3.0L but you will lose exhaust velocity by the time the 2nd turbo sees the exhaust and you are back to lag.

[Kristian_Wraae]

I know that running the turbos in parallel will cut the displacement in half. I assumed that there would still be a (slight) advantage using two smaller turbos instead of one big turbo.

On the other hand the manifold might also play into the equation. My HKS twin turbo manifold is rather old. Maybe some of the newer manifolds (like the ones Ron Ramirez makes) for a larger single turbo combined with a ball bearing turbo will show less lag than ball bearing twins on the older HKS manifold.

What do you think?

[figgie]

I know that running the turbos in parallel will cut the displacement in half. I assumed that there would still be a (slight) advantage using two smaller turbos instead of one big turbo.

On the other hand the manifold might also play into the equation. My HKS twin turbo manifold is rather old. Maybe some of the newer manifolds (like the ones Ron Ramirez makes) for a larger single turbo combined with a ball bearing turbo will show less lag than ball bearing twins on the older HKS manifold.

What do you think?


doubtful. Reason is that now you have about double the surface area to lose precious heat. A properly SIZED turbo will minimize lag and still get you in some high hp levels (yes 400 is high!).

[Kristian_Wraae]

Ok. I will take this into consideration.

How about the power delivery curve? Will there be any difference between twins and a single? Assuming both setups have been properly sized?

[figgie]

Ok. I will take this into consideration.

How about the power delivery curve? Will there be any difference between twins and a single? Assuming both setups have been properly sized?


Kristian

Depends on the configuration unfortunately, but there should not be a difference.

[foreverpsycotic]

Ok. I will take this into consideration.

How about the power delivery curve? Will there be any difference between twins and a single? Assuming both setups have been properly sized?

From what I have seen looking at HP graphs for MKIVs (aftermarket twins to single) is that the curve is a lot flatter, and power is delivered more smoothly. This might just be me however.

[Kristian_Wraae]

ok. If the twins are not going to be significantly worse than a single setup I'll go for the twins just for bling of it.

So I'll se if I can find a set of gt2554's

[figgie]

ok. If the twins are not going to be significantly worse than a single setup I'll go for the twins just for bling of it.

So I'll se if I can find a set of gt2554's


well couple of things to keep in mind.

double the oil lines. Double the returns (double the chance of failure). Intake complexity, exhaust complexity. Intercooler complexity.
Sensor placement (o2).
Relocation of any part that is "in the way".

All i have to say is make sure you do not bite off more than you can chew, you might choke! :naughty:

[Kristian_Wraae]

I have a few experienced friends that will take care of the fabrication. I also have a few pictures of the same setup on an other 7m engine so it might not be that big a problem.

But I'm reconsidering everything at the moment. I see someone is selling one of Ron Ramirez's exhaust manifolds/downpipes. Unfortuately it comes with a ITS GT76 dual ball bearing turbo which I think is way out of my league. If the piping will work with a smaller GT61-GT66 I might go that route.

[a_sesshoumaru]

what about this? once i thought that might work
two of these http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__OBX-Turbocharger-Turbo-Charger-MR2-MR-2-91-95-SW20_W0QQitemZ350085619950QQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQadiZ2865QQcmdZViewItem?hash=item350085619950&_trkparms=39%3A1%7C65%3A1&_trksid=p4506.c0.m245.l1318

and one of this http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__OBX-Supra-7MGTE-Twin-Turbo-Manifold-MA70-MK2-MK3-87-92_W0QQitemZ370075225492QQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQadiZ2865QQcmdZViewItem?hash=item370075225492&_trkparms=39%3A1%7C65%3A1&_trksid=p4506.c0.m245.l1318

i am using an obx turbocharger and i am amazed about the quality of the turbo, i have been running between 17 to 23 psi for six months everyday, today i inspected the turbo and it has no shaft play at all.

[Doward]

You do realize a .58 a/r T4 (60-1) will do what you want, and spool very fast?

Or, for that matter, a set of cams + 57 trim CT26 will hit over 400rwhp and spool practically instantly.

If you look at the entire system, you have less complexity, and it is easier to maximize a single turbo system. Notice that Toyota didn't stay with the parallel twins on the 2JZ.

[a_sesshoumaru]

i think this twin turbo idea is good for 800rwhp

[Kristian_Wraae]

I already have the HKS cast iron twin turbo T25 manifold. So no need to go OBX. Btw those OBX are not ball bearing turbos as far as I can see.

I found a set of GT2860R turbo's on ebay. I'm going to place a modest bid on those ans see if I'm lucky. That setup should be good for 600 hp. Hopefully it will not be too laggy.

How would you run the oil lines? I mean the 7M only has one oil out put for the turbo. Can you run them in serial, maybe with a small oil cooler between the two turbo's? Splitting the feed and run them in parallel will cut the flow in half, which I think is no good?

[a_sesshoumaru]

i think you need to raise the oil pressure a bit to compensate for both turbos. You might try to shim the oil pump and add another quarter of oil.

[figgie]

i think you need to raise the oil pressure a bit to compensate for both turbos. You might try to shim the oil pump and add another quarter of oil.


no

if the turbos are ball bearings, they require oil restriction on the inlets. A simple y split to the turbos should work fine.

[Kristian_Wraae]

Ok, and if they are not ball bearing?

Someone offered me a set of Garrett TB2531 turbos. They are journal bearing turbos. The 2.3L Saab 9000 used one of these to get to 200 hp.

I don't know much about them but I can get two for next to nothing.

The A/R on the exhaust housing says 0,49.

The good thing about them is that the exhaust port is very compact making it easier to fit them on the tight HKS manifold that I have. The down side is that it will not be possible to exchange the turbos for Garrett ball bearing turbos later on without making new downpipes.

Any idea how two of these Garrett TB2531 turbos will work on a 3.0 liter engine?

[Kristian_Wraae]

They look like this:

http://cgi.ebay.com/ebaymotors/Rebuilt-Garrett-T25-T-25-Turbo-Saab-9000_W0QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247QQcategoryZ33742QQihZ018QQitemZ280240772830QQrdZ1QQsspagenameZWD1V

http://www.japanerfusk.dk/19ce_1.jpg

I can get two for $400

[figgie]

No clue.

Older T series based turbo.

[Kristian_Wraae]

Someone told me they will be good for around 500 rwhp at 1.2 bar.

I think I'll get them as a start and then later exchange for some newer turbos if I feel the need for that.

[a_sesshoumaru]

i think your idea is worthy but with bigger turbos, the twin turbo idea should be ment to get more than 600rwhp, otherwise you could do it with a single set up. Try with turbos with bigger compressors.

[Kristian_Wraae]

I just bought two brand new Garrett T25 turbos.

They are rated around 250 hp each. So that should get me into the 400 hp range.

I really don't want more than that since 240 hp already scares the shit out of me.

But the route has been chosen:

7M-GTTE it will be.