thewird

iTrader: (8)

I remember reading somewhere that boost spikes if you hook up your boost controller (Profec Spec 2 in this case) before the intercooler instead of on the UIM.

Recently, there was a case of boost spiking and I couldn't figure it out thinking it was tune related but eventually got it to stop by setting the GAIN to 0 and GAIN% to 5% (the lowest it will go). After some thinking I remembered reading about the spiking if the controller is hooked up pre-intercooler and asked the person if they had their boost controller hooked up this way and they said yes.

Can someone explain why you would get massive spiking with the boost controller connected before the intercooler instead of on the UIM? Or if someone knows where its stated link to it. Thanks.

thewird

moconnor

iTrader: (14)

I've never heard of anyone measuring boost pressure pre-intercooler. Such measurements will be completely inaccurate because of the pressure loss of the intercooler - which will vary by rpm and boost - so will not reflect manifold pressure.

The signal the boost controller is working from will be different from manifold pressure so anything is possible. In any case, it is a bad idea.

thewird

iTrader: (8)

Anyone else? I'm really interested in why it does it. Understandable that the pressures are different but why does the spike only happen during spoolup and then seems fine afterwards?

thewird

DaleClark

iTrader: (55)

In general, with boost controllers, you want a boost reference that's as high and pure as possible. Using the nipple right off the turbo compressor outlet is best - you are measuring the real output of the turbo itself.

Measuring boost after the intercooler, or at the intake manifold, will show a lower amount of pressure due to the pressure drop through the IC, pipes, throttle body, etc.

The wastegate opens via a pressure source. If the wastegate (like the stock wastegate) is full open at 7 psi, and you have 7 psi at the turbo's outlet, there you go. If at the intake manifold at that same time you have 5 psi, you'll be holding the wastegate partially closed, creating more boost, and potentially making a spike.

Using the intake manifold as a reference is a trick that works on some cars to increase spool time or increase boost. IMHO, it's not necessary on an FD.

I'd have to know a lot more about the car to answer the problem of the spike, but that covers the theory of the matter.

Dale

thewird

iTrader: (8)

So having it connected at the turbo is the correct way of doing it? How come the boost controller manual shows to connect it just before the engine after the intercooler?

thewird

IRPerformance

iTrader: (41)

I like to source the boost from the compressor. That seems to provide the fastest response. That being said, the spec 2 is a piece of crap in my opinion. It doesn't usually work well with fast spooling turbos.

TpCpLaYa

iTrader: (10)

what do u recommend?

IRPerformance

iTrader: (41)

If you are on a budget, the Spec S works decent or aem true boost.Mid range would be something like the Blitz dsbc r. If your budget allows the sbc-id or greddy e-01. The spec 2 just doesn't seem to be consistent. I was disappointed because it looked so much better then the old profec b.

Sgtblue

iTrader: (16)

I don't have either...currently. But from what I gathered, the 'S' is essentially the same controller, but with fewer fine tuning abilities. No?

thewird

iTrader: (8)

Hmm, I didn't think it could be a limitation on the Spec 2 since it always seemed to work fine in my car and I could properly adjust the GAIN settings for best response.

The turbo was a GT35R so yes it spools quick, maybe that is the reason. The Spec 2 just isn't quick enough to the fast spooling of the turbo?

I'm also getting a 500R-SP soon so maybe I'll get into this problem on my car as well so I might need a new boost controller too.

On another note would he "Blitz Dual Spec R Boost Controller" be the same as the "Blitz SBC-ID Boost Controller" minus the bling? I really like the small formfactor of the Spec2 and how you can mount it above the steering wheel (next to my PLX m-300 wideband). I'm assuming they will perform the same.

thewird

IRPerformance

iTrader: (41)

I played with one in my personal car for over a month and no matter what I did it would be very inconsistent. For example, I'd get on boost once and get 15 psi, then again and get 17, then again and get 14, and so forth. This was all back to back. I have also had similar results with this controller is customers' cars. Honestly, the old Profec B worked better than the newer renditions, but its outdated and will look right at home next to an atari. Granted I had one of the first ones in the US, but I have never had good results with it. The Blitz is a much better boost controller in my experiences. The ID has a few more features and a better learning mode, but the Spec R works great as is. The 500R will spool slower than a 35R but have more power potential and hit harder.

fd3s400438

ok check this out . I have a 96 Fd , engine ported , 8:1 compression , apex seels ceramic 3mm etc . So it is a fairly strong engine

Apexi ECU , HKS T04E turbo kit with monifold and HKS wastegate , massive blitz intercooler , 76mm exhaust with no CUT , big injectors

Anyway the list is massive

I believe the HKS T04E is a small turbo with 0.64AR compressor , 0.84 AR exhaust

I think HKS will rate this at 400BHP max at the wheels

I am using my second , brand new Greedy profec spec 2 because I thought the first one was not working fine

Guess what , the second is not working either

My target is 1.3-1.35 bar or boost . Up to 1.1 all is fine

But no matter what settngs I use all I get is a boost spike - overboost call it what ever you want that goes all the way up to 1.45 and then it drops straight away down to 1.1

So I cannot see , ever constant -steady boost more than 1.1

I have tried to set the GAIN from 10% up to 35% , the set gain from 0.5bar up to 1.05 bar and the boost % ( first reading ) from 50-75%

All I get is a massive overboost which drops-dies straight away to just over 1 bar

WHY can I not see a steady boost more than 1 bar

Do you recon my Turbo is too small for 1.35 bar? I have a 0.6bar HKS spring. Do you think a 1 bar spring would be better?

I am lost

Ball joint

iTrader: (6)

I'm running non-sequential twins and my Spec-2 is hooked up before the turbo. The boost controller has always held a rock solid 14psi and I've ran the controller for over 4 years. Maybe this is more of an issue with users configuring the controller to control an external gate. I've hooked up spec-2's on a few FD's and have never had a problem with the controller on stock twins.

arghx

iTrader: (3)

What is the boost with the controller off?

fd3s400438

with the control off I get 0.9 bar. The original spring was 0.6 but has been stiffened to 0.9

I just came back from a test run. I got up to 70% boost , gain 6% , set gain 0.8 bar and it is still hitting almost 1.4 bar and dropping down to 1.1

Something else I noticed. When I am cruising along say in 3rd , 3K rpm and I floor it I get 1.4 overboost and the cars feels like taking off towards the moon

If I do a standing quorter mile and change all gears properly I only see 1.2 dropping straight to 1.05 with NO overboost and the car feels slower both to me and also feels slower revving as well

God I am so confused

arghx

iTrader: (3)

set gain is too high. try dropping it to .4 or .5

vosko

iTrader: (4)

i also second the motion that i do not like the spec s. it's way too intensive to "tune" it properly.

no_more_rice

Use a Hallman manual boost controller with cockpit mounted adjuster. Rock solid boost control, no electronic bullshit. Keep it simple with these cars and they won't blow up.

ksu-chewie

iTrader: (14)

I have not added an EBC to my FD yet, but I had a Profec B spec 2 on my (neon) SRT-4 when I had the stock turbo as well as when I upgraded to a 50 trim. The stock turbo on the srt-4 was small, TD04LR-16Gk, so it spooled pretty quickly. I was able to tune both turbo's with the spec II with very little spiking, if any. I had the controller sourced directly from the compresssor. There were a lot of people in the srt-4 community using the spec 2, so I'm surprised to hear of the difficulty with the FD.

arghx

iTrader: (3)

the only thing wrong with the Spec II is the confusing instructions. Everything else about it is the same as the other boost controllers of its type (HKS EVC-S, TurboSmart e-boost, AEM Tru Boost, etc).

if anything, the problem with the Spec II and all these external electronic controllers is that they're not complicated enough. There aren't enough settings to compensate for changes in the weather and engine conditions. If you look at how modern boost control systems are engineered from the OEM's, they are optimized to make the engine run as consistently as possible.

fd3s400438

VOSKO are you refering to my post with your comment :

i also second the motion that i do not like the spec s. it's way too intensive to "tune" it properly.

If yes what do you mean??

arghx

iTrader: (3)

^ I think he confused the Spec S and the Spec II. The Profec-S is the one with the *****. The Spec II is the one that everybody complains about.

KKMpunkrock2011

iTrader: (5)

saw your post in the other thread, what size wastegate?

vosko

iTrader: (4)

sorry i meant Spec 2 not Spec S. oops

Gorilla RE

iTrader: (1)

True and true.

-J