I fitted a FMIC over christmas on a 1993WRX and have an appropriate map running, and while the power above 5k RPM is fantastic I have a few problems down the lower end.

Its always ben lacking low end torque below 3k which I expect from a 1993 with a TD05 turbo, but it doesnt really come on power untill 3700 rpm now and it fells very 'sudden' when it does come on, not smooth like it used to be prior to the FMIC. Is this a downside that many have experienced with a front mount?
Will

 

Lag due to the extended pipe work. The turbo will spool up slower at the low rmp this would be even more notable on the fmic.

Also you mention the appropriate map i assume this was done after the fitting?

 

There shouldn't be any appreciable increase in boost threshold with an FMIC. It wouldn't be unusually to see better spoolup due to cooler intake charge after a sustained period of hard use. However, I would expect an increase in lag, ie the delay in time before you get boost after going WOT at some useful RPM.

You may find that you haven't lost anything in the low RPM zones, just that you've gained more at the top.

 

I did some spool tests on my P1 as follows-

a) RCM Garret P18 hybrid and all the support mods with a STI V8 TMIC, with a BRD map to suit

b) Exactly the same set up about a month after with a Hybrid FMIC and a BRD map to suit

From 2000 RPM in 4th gear, foot flat to the floor on the same bit of level road a number of times.

Its difficult to keep your eyes on the tacho, boost gauge, road at the same time but in specification a) i got 1.0 bar boost at 3500/3550 RPM.

In specification b) i get 1.0 bar boost at 3650/3700 RPM.

Its as scientific as i could make it given the circumstances, but it made max 200 RPM difference. This is more than outwieghed by the power/torque improvement with the massively lower charge temps.

this is all with a turbo/set up in the 400 BHP region.

 

There is definate a slight increase in lag, eg 5k rpm held steady off boost then floor it and it takes a split second to generate the boost but I'm not concerned about this.
It may be like you guys have said, more power at the higher end, I did get bigger injectors at the same time so it could well be that the car is simply pumping more power out. Think I'm going to take a trip to the nearest RR to get a power run in for a better idea of how its behaving.

Would I know if there was a leak in the pipework? I'm currently running with a dawes device set to peak at 1.1 bar but it does drop off/oscilate slightly from 1.1 to 1.03 bar when pushing it to the redline, didnt know if this was normal or could indicate a leak, I cannot hear any air escaping when in the cabin.

 

If you have fitted larger injectors you need to get it mapped to suit.

 

i had a fmic on my 94 wrx type ra but was routed differently to shorten pipes but still more laggy than top mount but power came in more aggressively and is certainly safer for charge temp than top mount...swap it back if yo uaint happy mate !! i personally love the fmic surge that you get !!

 

Have got hold of a map designed for a WRX with 440cc injectors and a FMIC along with de-cat and induction kit from andy at ESL. Very little knock activity (lights the second green on knocklink near to redline) at 1.1bar.

rabskyline : thats exactly what it is, a surge of power, seems to build up quite rapidly but then all of a sudden you get a massive push in the back. Having driven it for another couple of days now I don't think that it is missing any more low down power, its just pushing harder and more suddenly at the top end than before. Will have to get used to it.

The only thing that is really bugging me now is that for some reason my HKS dump valve is only functioning at boost over about 0.7bar, under that and I get a sort of chatter from the Induction cone and can clearly hear the turbo blades chopping the air as its pushed back the wrong way through it. Anyone had this before and know how to remedy it? I have the autobahn88 intercooler and the dump valve attaches just before the engine intake, not right after the turbo. This is daft in my opinion as surely you want to vent the pressure as close to the turbo as possible in order to relieve back pressure on it, or am I missing something?

 

I have the same thing also with the autobahn88 front mount kit.

 

You could try going back to the OE recirc dump valve, if you've still got it? Gotta Autobanh88 as well which I'm gonna fit this weekend to a 97MY. I've got some accel data for my car with the TMIC and am planning on doing a re-run when the FMIC's plumbed in so I'll hopefully have some plots showing the effect of the FMIC with the original maps (assuming all's ok with det) and again with 'optimised' fuel/spark.

 

Yeah still have it but its a bit of a plumbing nightmare to get it to fit with where the autobahn dump valve hole is.

 

Might be worth the hassle of sorting out an adapter for the old DV, - can't be a good thing if what your hearing is compressor surge.

 

i have been told ( not condoning it) that the mitsibushi td05 shafts etc are strong enough to run without a dv...i ran my evo 4 and my type ra without one and had no bother whatdoever .. i loved that chatter noise. going to do the same with my sti !!

 

I've been told the same. I plan to try it and see how it goes, although won't it upset the MAF with the airflow going back out via the air filter?

 

I also have the autobahn88 fitted to my Sti type Ra and get a slight chatter from the induction cone but the dump valve still works as it did even though i had to slightly bend the pipework to fit, Paul mapped the car and i found hardly any difference in lag just purley more get up and go and boost holding stronger for longer it is a different feel to the delivery of power but i think its just a case of you getting used to it,

 

borat, this may be a red herring, but I once took my scoob into a garage for some work and on return the car didn't feel happy at low revs, and boost came in very late - although it did still hit peak boost, it came on later in the rev range. Turned out the garage had not done up a hose properly and there was a slight air leak.

The leak was audible in the cabin though this was on a TMIC with a grommet out of the bulkhead to run the boost gauge pipe, plus the car was running stock exhaust and cats.

Probably worth running round and making sure all your hoses are tight and leak free.

 

Mark : Your figures above are very interesting.
On five speed boxes I always log 1 bar in 4th after a few trial runs to get the turbo and headers warmed up. I do this on the same piece of flat road as you have done, three times in each direction and average the figures.
Another useful test with a stop watch is 1,700 rpm or 2,000rpm or whatever, 4th gear, then WOT to say 6,500rpm. Again three times each way. You can refine this from 2k-4k if you wish to investigate the bottom end effect only.

 

A year ago I changed to a FMIC (from Harvey) from an Sti v8 TMIC on my modified Sti v3.
Had it remapped by AndyF who had to tweek the mapping.

No change in spool etc but big increase in boost and the time it can keep delivering it.

Suggest it needs re-mapping well.
Graham