I have a 93 with stock engine and turbos. When I bought it, it already had a home-made straight-pipe w/ cone filters - type intake, a dp, a universal 3" cat, and an Apex'i 3" catback exhaust. The car is my daily driver, with occasional track days. When I'm giving it WOT, I get a perfect 10 - 8 - 10 boost pattern, but I do get a boost spike during the primary to secondary transition of about 12 psi (occaisionally as high as 15). Would a boost controller prevent the spike, or is it more to regulate the "steady-state" boost? I've searched and read what I can find on the forum, and the boost controller manufacturers' web sites, but I'm just not "getting it" on this topic. If a boost controller is supposed to help this - would the manual needle valve types be adequate, or do I need to look at the electronic devices?

As far as the cooling system, I've drilled the thermostat, am using the Pettit underdrive pulley, and have a Koyo radiator. I'm running 40% ethylene glycol. I've not "ducted" the radiator yet. I use a Stewart-Warner electric WT gauge, with the sender installed in the filler neck. It shows 160 F when the stock gauge starts to move, so I think it's reasonably accurate. I typically get temps of 185-195 on the highway - up to 220 in city traffic on hot days, etc. On the track, last weekend, in ambient temps of 35 - 55 F, I was getting up to 240 F after several laps and having to back out of it. It is a fairly tight track, so it's not optimal for cooling, but given the ambient temps, something is obviously not right. The car cools right down to 190 when I run it at 55 mph in 5th gear for a few minutes. I've done the champagne bubble test since, and don't see any bubbles, so I don't think I hurt the coolant seals. I'm putting it on the dyno this afternoon to see if it's leaning out at WOT. If that's not it, I'll pull and flowtest the radiator. If it is too lean at WOT, I presume I need to modify or upgrade my ECU. My question (finally) is: would modifying or upgrading my ECU have any impact on the boost spike I describe above, or would I still need a separate boost controller?

 

As far as cooling goes I don't have any advice for you. Contact Mahjik or sleepR1. They track they cars so they would be able to tell you about temp conditions.

If you go with a PFC as a stand alone ECU: it has a boost control feature. Here is the kicker though, some people can control boost effectively with the PFC but for many they still need a boost controller.

Bottom line- Yep you need a seperate boost controller to eliminate your spike.

 

My guess is that you don't have adequate air flow through the radiator, since you say you have not yet ducted it. None of your other described situations or modifications seem like they would cause this type of overheating.

On the boost control, I'm still learning, and I think I know the answer, but I'd rather let someone else who really knows reply.

 

you need to quit that or get an ecu or you will pop your motor. check out damian's manual boost controller setup. search for it. youll find it. youll love it.

 

OK, got the dyno results. I'll post as soon as I can scan it in.

Max hp = 224 Max torque = 208 lb-ft
A/F 11:1 between 4000 and 7000 rpm
12:1 above 7000 rpm

Is this lean enough (in rotary parlance - it's still fuel-rich compared to stoichiometric at 14.7) to be a problem?

As far as the manual boost controller - if I just run the MBC for the wastegaste control (not the turbo prespool) can I control that transition spike without affecting my primary boost?