My R34 Gtt Runs Slower Than Stock After Few Mods. Plz Help!

[Flecher]

Hi everyone,

I felt like my car runs slower and rev slower than before after i installed a new intercooler on it. It is a cheap china fmic. Other mods are Apexi pod filter and Trust PE2 catback.

Somebody told me that it is because of the intercooler which slow down my car. Someone told me i need to replace the coilpack.

What should i do next to boost up my car?

p/s: i feel my car got fuel cut at 5500rpm but got fixed after service my car.

[R31Nismoid]

Did you dyno before/after?

Have you dyno'd at all to check?

How much boost?

Have you checked the usual things like plugs, AFM, CAS timing and so on?

[GT-RZ]

Well if your power went down after your intercooler install id be looking at that first. Personally wouldn't be buying a cheap intercooler. If you get one with crap flow resulting in a pressure drop @ the other end your turbo will have to work harder to keep the same power... Or in your case will just make less power as you didn't change the turbo boost?

If your last problem at 5500rpm is fixed forget about that for now.

[Krishy]

what gapping in the plugs are you running? If still the stock ones which is 1.1mm then i would be looking at getting it regapped at 0.8mm and see if that makes some difference...

[Howie]

I've got identical mods to my car, Trust PEII, Pod Filter, and Apexi FMIC... also a Nistune ECU. I lost about 9rwkw on the dyno after the FMIC install, which my tuner says is because boost had dropped after installation of the additional pipework for the FMIC. Basically it's begging for more boost now. The solution was to get a boost controller or in my case a HKS adjustable actuator... the HKS actuator works an absolute treat by the way. It's now sitting pretty on 11.94psi, and feels 100% better.

[skylinecouple]

This may be a pain in the arse but take the bumper off if necessary and check every bloody clamp and feel how far the cooler pipes are in the connectors. Years ago I used to get people who were so called mechanics to install an intercooler and it's amazing how some of them are just useless and couldn't give a shit. After they bolt everything together you should double check every bolt and clamp. If the only thing you have changed is the cooler and you haven't upped the boost it will be the cooler or clamps or connectors. Logic.

[Howie]

^^ what Gary said.. take off the bumper, check the clamps, etc.

Although I still think it's because of the additional plumbing that you're dropping boost. This is my setup.. I would've been surprised if it didn't drop boost.

[R31Nismoid]

How does it drop boost?

Just because there is more pipe does not mean it drops boost - thats absurd.

All it means is there will be a little more lag time - boost pressure should not change, just the volume you are filling

[mad082]

you can't drop boost by adding more piping unless your turbo is tiny and can't supply as much air as what your engine is using. your wastegate is controlled by boost pressure. it won't open until a set pressure. if you add 400m of extra piping the wastegate still won't open until you reach that set pressure. if you saw a pressure drop on your gauge after putting in the cooler then your cooler is more restrictive than your old one (but you would only see this if your boost controller reads from before the intercooler and your gauge from after. if your boost controller gets its pressure from the stock location on the pipe going up to the throttlebody and your boost gauge reads from after the cooler there should be no drop. if you noticed a drop in pressure and have the controller before and gauge after setup, then if you hook the gauge into the line the boost controller is using you will find that your boost pressure magically jumps up by a few psi without even touching the controller. this is because the before/after setup adds a restriction between where the turbo reads it's boost and where you read what is going into the engine. this also probably accounts to why some people blow stock turbos quicker than others at higher psi. if you have a restrictive cooler and are running 14psi according to a gauge after the cooler, your turbo may actually be running 16 or 17psi, where as someone with a good cooler may only be running 15psi when the gauge reads 14psi.

if you lost 9kw from putting on a front mount, then the cooler must be a really really bad design, as you should gain power simply from the extra cooling effect it has to the heat box that the stock intercoler is. was that 9kw loss from a run done on the same day on the same dyno and within a few mins of each other to make sure it wasn't due to different air temps?

looking at your setup i would say that your power loss would be due to the intercooler design. i'm not a big fan of the cooler setups that use the stock piping route. the length of the piping compared to the type that goes over the radiator is minimal, and the drivers side end tank just screams turbulence. at least with the normal style cooler the air is flowing in a straighter line

[Howie]

Yes, point taken... your logic sounds right.

Edit : Just doing some research (yes i'm bored) about this topic.. and people are saying it's not unusual for a horizontal flow design intercooler to reduce total overall pressure throughout spoolup and once spooled. It's usually 1 or 2psi and usually for such a small amount it's not all that noticable and can be compensated with an MBC. Which sort of reflects what my tuner was telling me.

I'll see if i can find any more articles off autospeed or howstuffworks when I get a chance.

[Flecher]

I've got identical mods to my car, Trust PEII, Pod Filter, and Apexi FMIC... also a Nistune ECU. I lost about 9rwkw on the dyno after the FMIC install, which my tuner says is because boost had dropped after installation of the additional pipework for the FMIC. Basically it's begging for more boost now. The solution was to get a boost controller or in my case a HKS adjustable actuator... the HKS actuator works an absolute treat by the way. It's now sitting pretty on 11.94psi, and feels 100% better.

Howie are you using GTR engine? I saw red cover in your engine bay. Aparently i don't have aftermarket ecu. I feel my car is not as responsive as before after install the apexi pod, pe2 catback, cheap china intercooler( later shit i've spent so much just to fix the crap piping as they always come off but got fixed by RE Customs by welding lips at the end of each piping) at once.

I was told by RE Customs that i need to change the coilpacks and later ecu reset or remap in order to run in higher boost. I did change the sparks plug at 0.7mm since my last service at RE Customs and got my boost controller disconnected by them. I think the clamps should be no problem as they tighten it for me. So do i need to change the coilpack and get a boost controller in order to boost up the car?

[Howie]

No RB26DETT.. just painted covers

You wouldn't have a dyno sheet, or anything else that would show your boost would you? I wouldn't mind having a look at it. Should only have to swap coil packs if you're having spark problems ... having said that I already had splitfires in mine, so i'm not sure how touchy factory 34 coilpacks are.

[(OO)SKYLINE(OO)]

^^ LOL! beat me too it.

Howie has just painted his Rocker / Cam cover Red thats all.

He still has a RB25DET.

[Flecher]

No RB26DETT.. just painted covers

You wouldn't have a dyno sheet, or anything else that would show your boost would you? I wouldn't mind having a look at it. Should only have to swap coil packs if you're having spark problems ... having said that I already had splitfires in mine, so i'm not sure how touchy factory 34 coilpacks are.

Oh ya. When i get my car to service last time they didn't put my car on dyno as they said it's my coil pack problem that slows down my car. So i dont have the dyno sheets. They disconnect my boost controller and reset the ecu. Change sparks gap at 0.7mm, service the car and tighten the intercooler piping. Apparently the car drive smoother but still not faster.

Oh ya, i forgot to mention that my r34 gtt got pop up screen at the centre instead of triple cluster gauges.. >.< so can't read the boost..

[mad082]

Yes, point taken... your logic sounds right.

Edit : Just doing some research (yes i'm bored) about this topic.. and people are saying it's not unusual for a horizontal flow design intercooler to reduce total overall pressure throughout spoolup and once spooled. It's usually 1 or 2psi and usually for such a small amount it's not all that noticable and can be compensated with an MBC. Which sort of reflects what my tuner was telling me.

I'll see if i can find any more articles off autospeed or howstuffworks when I get a chance.

the pressure drop they are talking about can be caused by 2 things. 1 is restriction. if something is restrictive then the pressure on 1 side is lower than on the other side. this is how a boost controller works. the other pressure drop can be caused by the cooling affect. cold air is less dense so takes up less space. this results in lower pressure on the engine side of the intercooler than on the turbo side. there are videos on youtube of a balloon being put in liquid nitrogen which graphically show this. the stock intercooler is small and suffers from heat soak rather quickly so after a few hard accellerations in a short period of time you won't get much cooling effect from it and will also have higher pressure in the piping (although same amount of air) due to the higher temps

Howie are you using GTR engine? I saw red cover in your engine bay. Aparently i don't have aftermarket ecu. I feel my car is not as responsive as before after install the apexi pod, pe2 catback, cheap china intercooler( later shit i've spent so much just to fix the crap piping as they always come off but got fixed by RE Customs by welding lips at the end of each piping) at once.

I was told by RE Customs that i need to change the coilpacks and later ecu reset or remap in order to run in higher boost. I did change the sparks plug at 0.7mm since my last service at RE Customs and got my boost controller disconnected by them. I think the clamps should be no problem as they tighten it for me. So do i need to change the coilpack and get a boost controller in order to boost up the car?

firstly if they disconnected your boost controller then you are probably running less boost which will make the car slower. but if you have a missfire issue then running higher boost won't do much.

to raise the boost you will need a boost controller. if you are having missfire issues at your current boost level then you will need new coils. you won't need a new ecu to raise the boost a little bit. you can generally go to around 11psi easily on the stock ecu, however your coils may let you down before you get that high.

as for your loss of response, you do lose a touch of response with any FMIC due to the larger piping, however with a decent one it will be minimal as it still flows well. with a crappy one it can make response even worse due to poor flow.

but think the main issue you need to fix first is your coils. get that problem sorted before blaming other things

[Howie]

Thanks for that explanation mad082 .. makes sense.

[Flecher]

thx mad082.. so what shall i do next when i had changed the coils in order to make the car runs more responsive and faster? shall i get an after market boost controller? is yellow jacket coil packs good? i 've heard good feedback from them.

[R31Nismoid]

My post still stands... dont just assume its one part - do some investigation - or preferrably take it to someone who can show you and/or check the car (mechanic or otherwise)

Did you dyno before/after?

Have you dyno'd at all to check?

How much boost?

Have you checked the usual things like plugs, AFM, CAS timing and so on?

[KiwiRS4T]

GTT smic will support 200- 220AWKW. Get a boost guage!!!I would spend the money on 1. Split dump 3in front pipe 2. Nistune chip for your ecu 3. electronic boost controller 4. better fuel pump...next stage bigger highflow/turbo... next stage even more boost,bigger injectors fmic. (Actual power at each stage will depend on quality of tune - you need Nistune chip or aftermarket ecu e.g. Vipec).

[Flecher]

My post still stands... dont just assume its one part - do some investigation - or preferrably take it to someone who can show you and/or check the car (mechanic or otherwise)

Did you dyno before/after?

Have you dyno'd at all to check?

How much boost?

Have you checked the usual things like plugs, AFM, CAS timing and so on?

erm.. i didnt put on dyno as the guy at RE Customs asked me to change coil pack first before they remap my ecu and put on dyno.. i did my car service there last monday so i think it should be fine as they did overall check during the service.. i'd changed the plugs..

i reckon i gonna save up for the coil packs and change them during the next service and put on dyno and see how it goes.. i wonder if yellow jacket coil packs are good?

there's some problem when i rev around 2500rpm when the boost & suction noise bout to build and i will hear premature air surge from pod filter and i wonder if it's a leak?