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Discussion Starter · #1 ·
Recently there have been some topics about T7 running lean after fitting a bigger/better intercooler.

After fitting the big Elksport intercooler on my NG900, bhp has gone up from 270 to 286. This is very close to the limit of the B204L fuelsystem. 290 bhp seems to be the maximum for the stock fuelsystem (injectors, FPR, fuelpump).
The Hirsch Performance ECU is mapped for the 270 bhp hardware.

How will T5 cope with this?

Does it adjust the amount of fuel that's injected when it notices the engine is running leaner than before?

Will there be a CEL when the engine is running (too) lean?

 

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You're getting more air into the engine so T5 will measure a greater air mass and inject the correct amount of fuel for that air mass. Up to the limit of the fuel system, there will be no problem.

Beyond the limit, assuming it's the same as the 9000 with T5, you will not get any warning of lean running.
 

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Running a lot of cooling mods, such as an uprated IC, cold air intake will reduce detonation significantly by keeping the cylinder temps down. Witness Mark in Irelands 9000 Carlsson which was making 340bhp+ on the standard injectors, I also know of a T8 c900 that is producing in excess of 200bhp and that has a large FMIC fitted*. So I wouldn't assume that because you have an extra 16bhp that you are that much closer to the point at which detonation will occur.


*Keep your eyes peeled for another Midlands RR day and hopefully we'll be able to verify the power/torque and boost of this particular car.
 

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Sounds like it is doing great, Maarten! I think you should be ok, considering, with similar mods, Maptun shows up to about 290 hp on their site, or at least they used to. Anyways, I will have the same concerns once I get my MP intercooler installed and maybe an upgraded turbocharger.
 

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Discussion Starter · #11 ·
Originally posted by Rob12:
[qb]I still have the standard T25 turbo ![/qb][/b]
Don't change the turbo unless it's broken. When Eric had his 9-3 mapped by Hirsch, specs were almost the same as on my car exept for the turbo. Eric had a Garrett T25, I had a Mitsu TD04. IIRC it made a 10bhp difference.

/john's car is a good example of how far you can push a T25. He's using the Elksport intercooler, 3" downpipe and a Hirsch catback exhaust.
 

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Witness Mark in Irelands 9000 Carlsson which was making 340bhp+ on the standard injectors,  [/b]
That was also with the standard intercooler, however I now have a full size 70mm thick one which Allards made for me and I have left my old intercooler with them to assist anyone else who wants a bespoked cooler making.
Mine cost £420 all in including postage and its a nice job too....just don't have the time to fit it
With regards to the T25 turbo, I reckon they can last as long as the boost is kept to about 1.4 bar max, I ran 1.6 but the 4 wrecked turbos on my bench is testimony to the reduced life span.
 

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Originally posted by Maarten (900 Hirsch):
[QB]Recently there have been some topics about T7 running lean after fitting a bigger/better intercooler.[/b]
I don't see any reason why you should run lean. I recently discovered that T5 is a freak amongst MAP sensor fuelling systems; it doesn't measure static pressure like all other MAP sensor'd cars do. The MAP sensor in the T5 throttle body faces "into the wind" so to speak. That means it measures total pressure instead. At any given total pressure and temperature of air through a fixed size throttle body, the mass-flow is constant. The same cannot be said for other MAP systems which use static pressure.

If there is an increase in airflow from better VE or drop in intake temps, even though the "boost pressure" (static pressure in disguise) remains the same, the MAP sensor will sense the increase in airflow and fuel accordingly.

It's rather ingenius actually and I'm suprised more other manufacturers haven't caught on.


Adrian W~
 

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A tuner who has played around with these cars alot told me that T5 cars do generally run leaner after IC change. He could not give a specific reaon why this happens, but it does.
Might be worth to get the car tested after mods just to be sure.
 
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