Rolling Road

[jerryd_33]

Hi all,
Any of you chaps had your cars on one yet?

I did.

Did not sound or look impressive at first. But taking into consideration I could not get the stupid " FELINE " thingy off and " getting fuel cut in HIGH BOOST ", I am looking at 200.8 HP at the wheels. This was acheived in LOW BOOST.

Does anyone know the % or ammount of loss would be through the transmison?

[Wodjno]

I think losses are around 24% ! but don't quote me ..

[Wodjno]

for an auto that is !

[Kieran]

Yep, the 'Accepted' figure is 24% loss, plus 7% through the torque convertor if it's an automatic. To be honest we have no idea how accurate this is - We use it because it tends to be the norm on the MLR and also if everyone uses it then it does at least level the playing field.

The wheel horse power is the important one though. 200bhp on low boost calculates as 280bhp (assuming it's an auto). Doesn't seem too shabby to me?

[Wodjno]

so it's 24% for a manual.

and 24% for an auto + 7% xtra..

i'm sure I remember a deep discussi0n ab0ut this after our last club rolling road..

its on the forums somewhere ..

[Kieran]

Here it is:

http://www.clubvr4.com/forum/showthread.php?t=23350

[jerryd_33]

MMM!!!!!!!!!!!

28%!!!!!!!!

That does not sound like alot. Makes me think the work I have done on my car is disappointing.
But now reading the linky above. :inquisiti :inquisiti /Grrr

[Kieran]

What have you had done Jerry?

[Nick Mann]

200 at the wheels is a resonably modified car, IMO. Standard VR4's can have a lot less than 200! Heavily modified cars in the UK don't often get above 220-230 ATW.

[Davezj]

MMM!!!!!!!!!!!

28%!!!!!!!!

That does not sound like alot. Makes me think the work I have done on my car is disappointing.
But now reading the linky above. :inquisiti :inquisiti /Grrr

What fuel were you using as can make a difference!!

[jerryd_33]

Had filled up with V-Power .
What have I done to her,

1. Changed some of the turbo piping for a combination of silicone and ally piping ( compressor outlet )

2. BIGGER INTERCOOLER

3. BIGGER TURBO x 1

4. H2O injection ( not yet got that working ).

Looking to have the MAP-ECU fitted and mapped.

:evilgrin: :evilgrin: :evilgrin: /rally /rally /rally /rally

[bradc]

1x bigger turbo? you mean you replaced one td03 with something better, or you replaced both with a big single?

[jerryd_33]

Hi bradc,

I replaced the rear with a bigger one as used on a 200SX. It only just fitted in place and NO ROOM for anything bigger.

[bradc]

and umm what about the front one? Thats gonna be bad for the engine having mismatched turbos

[jerryd_33]

Actually its not.
Our cars are not like the GTO with two seperate intercoolers. Both turbos feed one intercooler.
Dirving her, she feels a hell of of alot better. It feels like the car has got a lot more grunt in her. And when I drove her hard once the bigger turbo blew off one of the compressor out let pipe.

[Nutter_John]

Err I think Brad is correct that by having mismatched turbos there will be an imbalance in the flow of the turbos , now this may not seem like much but your putting a lot of extra strain on the cranks as one side will be making more power than the other .

Have you got any fuel control in place and a way to view knock as the increase in airflow via the gt25/28 turbo will mean that you will run leaner on one bank to the other

[bradc]

If it was me I would put another turbo the same on the front

[Wodjno]

now this may not seem like much but your putting a lot of extra strain on the cranks as one side will be making more power than the other .


How does that work then John ?

Both Turbo's, whether both the same size or of different sizes ? They both feed up to the same manifold?

Each Turbo doesn't feed individual banks !! So the pressure would be equal.. ??

If any problem occurs it will be at the intersection of the pipe that feeds the manifold. What is actually happening here i don't know, but the flow won't be even as there will be air flow at 2 different speeds and 2 different heats ?

I'm not clever enough to work out what effect that would have /Hmmm /dunce

[Wodjno]

If it was me I would put another turbo the same on the front


Seconded /yes

[bradc]

at say 2500rpm the TD03 would be spooling, while the bigger turbo wouldn't be spooling. I'm willing to bet that would create big issues, the boost from the TD03 would be pushing down the 200sx turbo. At say 7000rpm the exact opposite would be true.

Now as for flow through the cylinders, they would be different, think of the different amount of back pressure generated by the turbos, at high rpm the td03 is obviously going to create a lot higher back pressure, making it more difficult for air to flow through, hence there would be less air flow through the front cylinders, and more through the back. Yet the injectors wouldn't know that and would be putting the same amount of fuel in, and there is only one oxygen sensor that takes the average of the two banks, and well....BOOM

[Davezj]

that seems like good point. i had not considered the back pressure issue. he probably carn't fit the larger turbo on the front bank without major pipe work mods.

[Kieran]

Well, some 3000GT owners have done the same, as briefly discussed here:

http://www.3si.org/forum/showthread.php?t=278599


However I doubt it's a good idea long term for the reasons Brad has outlined.

Also, I am not surprised at your result. All you've done is change a turbo and an intercooler - so you'll be getting more air through, but only a bit. I'd say you've created a rod for your own back as well... Start upping the boost and the bigger turbo will be okay but the little TD03 will be spinning it's nuts off!

[jerryd_33]

M!!!!!!!!!!

Bradc, he has put forward some very good points. But I shall soon be having a MAP-ECU 2 fitted to my car which will have the ability to sense O2 sensing via a wide band O2 sensor.

Also looking for a oil filter relocation kit so that I can make more space for a bigger turbo up front. Which I just happened to have laying arround fully rebuilt.

If anyone knows of such a filter relocation kit please can you send me the information or let me know if you can buy me one? Ofcourse I will pay.

[jerryd_33]

Hi Davezj,
pipe work is an issue but not at all a major point as that will definitely need altering with a different turbo. I already had to change and make new piping for all water (feed&return), oil (feed&return), compressor (inlet & outlet ) and exhaust.
I also changed the inlet piping for the front turbo giving it a smoother inlet air flow.
The only piping to be changed is the exhaust down pipe which I am not very happy with even though it is not a standard item.

[bradc]

You need two O2 sensors though, one on each turbo in your case of having two mismatched turbos

[Eurospec]

I would have thought with one bigger and one smaller turbo the ve on the 2 halves of the engine will be different, primarilly because of the different back pressures. That will lead to a difference in afr's between front and rear bank that you will only pick up with 2 x o2 sensors. In the downpipe it will all read fine, when it might be that one bank is lean and one bank is rich.

Unless you use external injector drivers, there is no real way to get round that.

I'd match up the turbos if at all possible. You may also notice surge on the set up as one turbo spools before the other, causing one to stall etc. You will notice it most as you come to the cruise. This is basically what Brad was saying.

Hope that helps,

cheers,

Ben.

[Turbo_Steve]

I think brad is bang on. When you turn up the boost, you'll drive a rod through the block. End of story. Forget all the ECU tuning, the fuel injection everything else, they all assume that this idea ia mechanically sound. It isn't. A V6 engine survives by being having balanced forces on both sides. If you're lucky, you'll kill the TD03 first. It's likely it will restrict that side of the engine so much that it's internal pressure will rise and you'll do the ringlands or the headgasket. It's more likely, however, that the amount of force being exerted by the other bank with the bigger turbo will result in the engine trying to compress air on it's exhaust cycle, resulting in high cylinder temps, and residual charge, which results in leanness as well as abnormal loading, which results in an expensive crunch.

There's nothing wrong in doing a sequential turbo setup, but I'd suggest you spend a bit on custom exhaust and inlet piping, and some external wastegates to control the flow. RX-7s do this to great effect and it would work very very well on our engines if you can afford to get the control systems right.

[Kieran]

Personally I'd listen to Ben and Steve. Also - reading one of your older posts, I presume you've now re-adjusted your FPR from what you mentioned here?

http://www.clubvr4.com/forum/showpost.php?p=298508&postcount=6