ImportAddict

Hi Guys,

I'm not being a cry baby or anything, but whenever i post a damn question no one replies, and then a week later some posts the same question and everyone is on top of it. My question is:
I heard from someone that the HKS EVC 4 eliminates the 10-8-10 boost pattern and just stays at 10 and doesn't drop down to 8, is this true? I'm trying to decide whether i should get the HKS or the Blitz sbc-id.
All the help would be appreciated.

Thanks

Man-Chun

If I knew I would help . Sorry I don't know anything about the HKS boost controller. But seeing as it is designed to control boost I would assume it would boost 10-10-10 instead of 10-8-10. If you don't get another reply I would phone your supplier up and ask him. I don't own a FD but have been reading info for a few weeks now, anyway sorry I couldn't help but I thought I would reply .

Chun.

Johnny

the drop to 8 is part of being sequential....I have not experience with either boost controller...but I have my doubts to whether either one can do that...hell I may be wrong

Man-Chun

From what I have read on these forums the PowerFC, I know its a ECU replacement, manages 10-10-10. But I would of thought there methods of boost control would be similar. I could be wrong.

Chun.

ImportAddict

Thank you so much for your replies. I am asking this because my mechanic Rick @ Rick's Rotories said that our cars are not supposed to have a 10-8-10 boost pattern and that the HKS eliminates that problem. My stock boost solenoids are no good and they're not letting me boost past 8, and i currently have a downpipe within a month I'm getting the Power fc, hks carbon ti, and apexi intakes. So I just wanted to see if theres a way to get my boost back up and keep it at 10.

Thanks

Toadman

If you're getting a Power FC, don't consider a boost controller. The PowerFC integrates it. I found Rick's fax number and am going to send him the service highlights stating that normal boost on the FD sequential system is 10-8-10 psi on the WOT test. No idea what he has been smoking and kinda scary that a rotary tech shop would be that ignorant of stock sequential turbo operation.

JONSKI

10-8-10 is stock, regular, normal, etc. Rick sounds like a newbie. Is he on the forum?

ImportAddict

Guys,

Rick knows that the stock boost pattern is 10-8-10, but i think that he mentioned to me that a HKS EVC just keeps it at 10 and doesn't drop down to 8. Rick has been working on rotories over 20 years and I'm sure he knows alot more about our cars then almost everyone on the forum. You know this because when you go to his shop you see at least 5 FDs there and he does his own rebuilding on engines, so he knows his ****. Sorry if i got some of you confused about him.

Thanks

mkoch1

The 10-8-10 is because of the way the stock seqential system works. I am not sure a boost controller alone can elimiate the 10-8-10 issue. Do yourself a favor and go single, it elimates alot of problems. Also I run the PFC and a greddy B boost controller.

Trexthe3rd

I sent you an e-mail response to your question earlier, not sure if you got it, but if some one is telling you that the transition boost drop is a problem then I would seriously consider using someone else. The sequential setup on the RX-7 is very complicated and designed to minimize boost drop during the transisiton period when the secondary turbo comes on-line. It does this by means of a prespool control that spins the secondary turbo prior to engaging, without the prespool the boost pattern would be more like 10-2-10 and the gap would take longer to recover. The prespool is controlled by mechanical means (a restriction pill) and can not be altered by the ECU or boost controller. There is no boost controller (or ECU) that can control the prespool function. The transition drop can be altered by replacing the stock restiction pill with a manual valve (see Rob Robinett's site), but is very tricky to get the correct setting, even then you will not get a 10-10-10 pattern. The only way to do that is to go non-sequential.
The only function of boost control (ECU or stand along) is to control the wastegate. The openning of the wastegate determines where the boost level is via a feedback vacuum/boost line. Integrated ECUs can change A/F mixture in accordance with the boost setting which is a good thing (prevents lean conditions). Stand alongs doesn't care about where the A/F is at, so you need to be sure the ECU you are using will provide sufficient fuel. I hope this answers your question. You can write a whole book on turbo control, this is the Cliff Notes version.

Trexthe3rd

One additional note, it is physically impossible to have a sequential turbo system without a transition (its an oxymoron). The only way for no transition to occur is to have the secondary spool up at the same time as the primary, but that would increase lag due to the extra exhaust load to drive both turbos and defeats the purpose of sequential boost and is essentially the same as none-sequential. No offense I'm sure Rick is a good mechanic, but I really don't think he knows the engineering aspect of the sequential twin turbo charging system.

Toadman

Well said, T-Rex.