Interesting Rolling Road Results

[futureal33]

Hi guys,
Just got back from doing a Rolling Road and Im a little dissappointed with the results. From looking at the graph you can see that my car pulls really well upto 5550rpm but then sort of dies, only coming back a little bit at around 6400 rpm.
The mechanic reckons this is due to the air/fuel mix running very very lean (far too much air) and then asked what mods I had:

17% Pulley
CAI
Milltek Exhaust
Janspeed Manifold

He said thats the problem, all those mods increase air flow but nothing is increasing the fuel, so when my car hits 5000rpm there is so much air in there that the fuel system 'shuts off' thus killing the power.
He said its causing early detonation, which is being prevented by something in the engine which is retarding the ignition at the cost of sacrificing performance but saving my engine from being destroyed by the early detonation.
He reckons a remap which increases the fuel will solve the problem. He also reckons that once the car has been remapped and the air/fuel mix thing is sorted out my car should be putting out about another 30-40 bhp, and by looking at the graph I can see what he means, if it keeps going the way it is, its gonna be off the 210 scale before the rev limiter

Can anyone back up this statement?

When driving the car it also reflects the graph very much, there is so much power and torque right upto 5k but then it just stops, the most noticeable thing is the noise from my exhaust, really really loud upto 5k, but then goes quiet until you change down and then its loud again as the lower revs kick in.

Thanks for any help

[uncle albert]

Hi mate,

My car is currently much the same in that power tails off at the top end, most likely due to running standard injectors, as show in the dyno plot below.



I've recently ordered some JCW injectors, which will hopefully improve things.

James

[futureal33]

What mods have you got on your car mate, you seem to have a very high BHP at the engine?

[Loui]

Mine has the JCW injectors an didnt have the drop off top end like uncle alberts did on same day an rollers

[uncle albert]

Quote: Originally Posted by futureal33 (original)

What mods have you got on your car mate, you seem to have a very high BHP at the engine?

GTT220
+1% crank pulley
GRS intercooler
Milltek cat-back

Standard cars running that day were pretty much on the money.

James

[futureal33]

Looks like larger injectors might be what I need.
I've been reading up on it and lean mixtures can cause major engine problems Deffo dont wanna go down that road.

Does anyone know what flow rate the JCW ones are and also how much they are? Im gonna have to get some asap to prevent any further damage to my car

[Rigsey]

James, do you need to change the map with the new injectors?

Mines booked in for a dyno run in 2 weeks :-)

[uncle albert]

Hi Neil,

Nope no remap required for bigger injectors.

futureal33, JCW injectors are 380cc compared to 340cc standard. Defo worth doing mate, as yes, a lean mix can end up costing you £££ down the line. I'd recommend not redlining the car for extended periods until you fit bigger injectors.

James

[Loui]

Quote: Originally Posted by futureal33 (original)

Looks like larger injectors might be what I need.
I've been reading up on it and lean mixtures can cause major engine problems Deffo dont wanna go down that road.

Does anyone know what flow rate the JCW ones are and also how much they are? Im gonna have to get some asap to prevent any further damage to my car

JCW injectors are 380cc

[futureal33]

Dont worry mate, since finding this bad news out I have kept the revs below 2500. Im gonna have to get something sorted ASAP.
Im just wondering which would be the better route:

MTH Remap which increases the fuel, this is what the mechanic suggested.

or

Larger injectors.

[Loui]

Quote: Originally Posted by futureal33 (original)

Dont worry mate, since finding this bad news out I have kept the revs below 2500. Im gonna have to get something sorted ASAP.
Im just wondering which would be the better route:

MTH Remap which increases the fuel, this is what the mechanic suggested.

or

Larger injectors.

Bigger injectors as leaning out the stock injectors by telling them to send more fuel when they cant is just as bad, as my mate who has been building a 4x4 mk3 astra turbo found out twice with crapy tunning advise from people calling themselves profesionals

[Rigsey]

This is getting me worried now...

How much are jcw bigger injectors and how difficult are they to fit?

[futureal33]

Quote: Originally Posted by Loui (original)

Bigger injectors as leaning out the stock injectors by telling them to send more fuel when they cant is just as bad, as my mate who has been building a 4x4 mk3 astra turbo found out twice with crapy tunning advise from people calling themselves profesionals

I'd agree with you, but UncleAlbert is running stock injectors and he still gets 230+ bhp off them. He will have had the MTH remap also as he's got the GTT220, and from the looks of his dyno it has worked very well for him. I agree with 230+ bhp maybe you need bigger injectors (the GTT website also says this)

I think I am going to get an MTH remap and make sure they squirt as much fuel in as possible, if I still have problems the JCW injectors are coming my way

But hopefully the MTH remap will sort my problems out.

[uncle albert]

Quote: Originally Posted by futureal33 (original)

I'd agree with you, but UncleAlbert is running stock injectors and he still gets 230+ bhp off them. He will have had the MTH remap also as he's got the GTT220, and from the looks of his dyno it has worked very well for him. I agree with 230+ bhp maybe you need bigger injectors (the GTT website also says this)

I think I am going to get an MTH remap and make sure they squirt as much fuel in as possible, if I still have problems the JCW injectors are coming my way

But hopefully the MTH remap will sort my problems out.

Sorry dude, my car is running STOCK map. And I have no plans to change this.

James

[futureal33]

Didnt you get a remap with the GTT220?
Your rev limiter is at 7200 though??