Austarion

Hey guys, I currently have a Garrett GT35 turbo on my car, with custom manifold, and haltech. It is running at something like 12psi and is getting 220HP in third gear, Or 170.9 in fourth. It currently has the two injectors, and the flexible small intercooler piping. What this thread was about was this.

I am upgrading to I think 2 1/2 or 3" intercooler piping, and the magna MPI with 4 magna injectors. And I will be getting a full retune, and running 15psi. What sort of increase would I be looking at getting or what sort of power will it be around after allowing the turbo and engine to flow more? If any :(

You'll have to upgrade the injectors (4x 880cc, on high % duty cyle enough for 300Kw atw), so MPI a necessity, 2 1/2" IC Piping is optimal for 450HP at the treads, sort out your fuel pump and fuel regulator aswell and then start looking at nice power increases from here on in :drool:

62-3mm t/b is suited to 2 1/2 piping, these t/bs' apparently exist in the N/A 4G63 DOHC Engines where the Turbo ones got the 60mm one instead suited to 2 1/4inch piping. If your really fussy, skim the overall outside diameter of the centre rod on which the butterfly turns on it's axis a couple of mill, radius the edges of the butterfly and it then shouldn't affect the pressure at all of the complete system by having inconsitent cross-sectional areas

That doesn't answer his question.

Yes Cookie, but all info helps.

I am going with a V6 Commodore throttle body. And the Magna intake is already modified. But you think that the injectors are too small? What about 360cc ones?

360cc would be too small. might as well do it right the first time and buy injectors that are well within your ultimate power goals.I would get 550cc's at least.

450cc injectors run roughly at about 80% duty cycle when producing 150rwkw. Optimally you don't want to run injectors any harder than this.

So if your looking at more power than this then, like NXTIME said, bite the bullet and get 550cc injectors or bigger.

360cc are definitely too small and will lean out under boost.

Cookiemonster wrote:That doesn't answer his question.

How long is a piece of string ? and it's not twice the distance from the middle either

550's will be okay till about 200kw atw, I think he is looking for more power than that with the turbo he has choosen..........

And you still have to deal with the camshaft issue aswell

rofl I dont the answer but I will at least answer the question asked - 50HP :?

toysrus wrote:

Cookiemonster wrote:That doesn't answer his question.

How long is a piece of string ? and it's not twice the distance from the middle either

550's will be okay till about 200kw atw, I think he is looking for more power than that with the turbo he has choosen..........

And you still have to deal with the camshaft issue aswell

the piece of string is as long as you want it to be :D

WidebodyWoody wrote:Hey guys, I currently have a Garrett GT35 turbo on my car, with custom manifold, and haltech. It is running at something like 12psi and is getting 220HP in third gear, Or 170.9 in fourth. It currently has the two injectors, and the flexible small intercooler piping. What this thread was about was this.

I am upgrading to I think 2 1/2 or 3" intercooler piping, and the magna MPI with 4 magna injectors. And I will be getting a full retune, and running 15psi. What sort of increase would I be looking at getting or what sort of power will it be around after allowing the turbo and engine to flow more? If any :(

Woody I would say you should be around 250HP+ at the wheel @15-16psi. Actually you should get around that now @15psi.
But the big difference with the Magna manifold is it should REALLY spool the turbo down low.
The TBI on the 2.6 is very restrictive I measure a 3psi pressure drop through it.

My Magna manifold is ready to put on just got to find the time and buy some injectors. Something around 600cc.
I think you could shoot for 280-300HP at the wheels @ 20psi with forged pistons, cam, big intercooler and piping.
Stock Magna regulator is fine however stock fuel pump would be marginal.

Make sure you post the dyno sheet!

Ahh look... an answer. :)

Thank you all. I might try and sell the set of injectors I got then, and go the RX7 550cc injectors. That would give me the best outcome for the time being. I do want to go for top power eventually, however, ATM I can only afford to upgrade one at a time. And after this lot of upgrades, I will be doing internals. ALL at once, cam, forgies, con-rods ect. Then I will wind the boost up to 20psi. I am hoping to race this car with this lot of mods at this years Brisbane Jamboree. And I will of course post up my dyno sheet. But I am hoping to god that I get a nice increase. My car is restricted by the inlet, cooler piping, and the injectors atm. I can not run any higher boost because I think my injectors are either on that 80% duty cycle, or on the full 100%. But I think it is more likely that it is on the 80%. And that is just the two injctors, that is why I thought that the 4 would cope. But I will go the whole way then. Will I need to upgrade my fuel pump though?

Speak with mrb1 as he would have an idea on how far the stock one can go

Try and play around with the MPI Manifolds if you can, there will be variations in them and you would want one suited more to top-end power than spool-up, since the 2.6L won't have any issues spinning your turbo so no real advantage from going to skinner/longer runners apart from reducing top-end flow = power loss :(

WidebodyWoody wrote:Will I need to upgrade my fuel pump though?

I think 250rwHP is getting very close to the stock pump capacity. You can do a basic check by putting a long bit of hose onto your return line from the pressure regulator and running it (just bridge the fuel pump relay) into a bucket beside the car for 30 or 60 sec and see how much flow you have. Make sure you do the test outside (ie. not in a garage or confined place) and nobody is smoking!

However be aware that the flow will decrease at higher pressures as it follows the boost up. Say you have 3 bar fuel pressure + 1.4 bar boost the pump will see 4.4bar fuel pressure.
So if somebody has a small pressure pump remove the manifold hose from the top of the fuel pressure regulator and connect say 1.4 Bar (approx 20psi if that's the max you will run) and do the test again (it will flow less than before). With these pumps you can actually hear the motor slow down as it works harder against the higher pressures. Anyhow if this flow still exceeds the capacity of your injectors then your ok.

Also be aware the EFI roller cell pump is a DC electric motor. It's speed is directly proportional to the supply voltage. So make sure you battery is fully charged when you do the test.

The testing method above is the absolute best way to test this because it takes into account every fuel line plumbing restriction (bends, joins, filters, etc) and also the electrical wiring peformance.
These pumps draw a lot of current you would be suprised how much voltage drop there is by the time it gets to your fuel pump. On most cars they have the longest wiring of any high current device fitted.

And before anybody asks me no I haven't done this test to my car(cars) yet
It's on my things to do list. However I have checked the JA (VL turbo pump) under boost with a fuel pressure gauge and it was holding ok.

From what I've seen so far with the 2.6 I agree with Mrb1.
I'd suggest looking through the starquestclub forum for ideas on power made with stock internals.