using an intercooler w/stock boost levels

greg donovan · Post by **greg donovan** » Sun Oct 31, 2004 5:06 am

i think that all turbo cars should be intercooled no matter what the boost level.

the first mod i want to do to my future car is an intercooler. however, i dont want to raise the boost at all.

would i see a gain in performance even on stock boost?

vrg3 · Post by **vrg3** » Sun Oct 31, 2004 5:20 am

It depends on the efficiency of the intercooler and the pressure drop across it.

When I installed my Saab intercooler I worked through some rough numbers and found that the actual airflow through the engine would be roughly unchanged -- that is, the cooling and the restriction very nearly canceled each other out.

Even at the same airflow, though, you should make a bit more power because spark timing can be a little more advanced.

It should be pointed out that stock boost control doesn't really work so well once you install an intercooler. I noticed at first that my manifold boost levels dropped down to about 7 psi, indicating that the intercooler dropped about 1.7 psi. But the ECU did slowly try to adjust boost control duty cycle to get back up to 8.7 psi in the manifold (which would translate to about 11 psi at the compressor outlet). It never got all the way, though... at some point it would just give up and then quit trying to control boost altogether (yielding wastegate boost -- about 5 psi in the manifold). Sometimes that point would happen almost immediately after an ECU reset, and sometimes it would happen after days or even weeks. So you'll probably want to switch to some other kind of boost control. RIght now I'm just using a 40-cent spring from the hardware store strung in parallel with the wastegate actuator rod, and it's working pretty well.

It's worth noting that even if you don't get much additional airflow, you will still improve your engine's longevity. The cooling system will be less taxed and EGTs will be reduced and stuff.

greg donovan · Post by **greg donovan** » Sun Oct 31, 2004 5:29 am

vrg3 wrote: It's worth noting that even if you don't get much additional airflow, you will still improve your engine's longevity. The cooling system will be less taxed and EGTs will be reduced and stuff.

this is the biggest reason i want to do it. i will already be gaining 35 hp and 50 foot pounds over what i have now so the need for more speed will be satisfied for a while.

i need to do some more MBC research as i have never bothered to look at any trubo related stuff as i was only dealing w/NA cars untill now.

but if i understand you correctly a MBC is a very good idea if i put an intercooler on it.

of course a boost gauge will be installed before i do anything. i need to know what the boost is.

douglas vincent · Post by **douglas vincent** » Sun Oct 31, 2004 6:49 am

I know I suffered a huge drop in boost, about 40%. Before I installed the AWIC and was running the small crank pulley, I was maybe 5 psi at most. Then when I installed the AWIC it dropped to 3 psi. Then I installed the huge crank pulley which was capable of close to 10-12 psi before the AWIC but now I am maxing out at 5psi. But then again, I am the only one superchargering. I am using the JDM AWIC and not having any problems with detonation but am still getting a J&S Safeguard.

NuwanD · Post by **NuwanD** » Thu Nov 11, 2004 5:42 pm

My boost gauge read a max of between 5-6psi after install the wrx intercooler (stock boost controller still).... the car felt much much faster as a result, lots more torque down low

BAC5.2 · Post by **BAC5.2** » Thu Nov 11, 2004 5:46 pm

What are you doing that'll give you 35hp and 50lb-ft?

legacy92ej22t · Post by **legacy92ej22t** » Fri Nov 12, 2004 5:26 am

A boost gauge ( I know you mentioned it already that you will get one) and a MBC are a must. Either build a MBC yourself or get a nice, cheap Joe-P or Hallman (Hallman's better). That way you can adjust for the pressure drop and keep the stock boost control from throwing a fit.

Even at stock boost levels the IC will make a lot of difference. The car will definitely pull harder.

greg donovan · Post by **greg donovan** » Fri Nov 12, 2004 3:54 pm

BAC5.2 wrote:What are you doing that'll give you 35hp and 50lb-ft?

selling my 90 fwd nonturbo to my brother and buying my friends 94 SS.

BAC5.2 · Post by **BAC5.2** » Fri Nov 12, 2004 3:56 pm

Oh. I already did that mod.

+1 94ss on the board.

greg donovan · Post by **greg donovan** » Fri Nov 12, 2004 10:35 pm

BAC5.2 wrote:Oh. I already did that mod.

+1 94ss on the board.

yep should be a pretty easy mod. looking forward to it. should get it the second week of dec. the car he is buying wont be available till after thanksgiving and i am busy untill later so...

BAC5.2 · Post by **BAC5.2** » Fri Nov 12, 2004 10:49 pm

What is he buying?

-K- · Post by **-K-** » Sat Nov 13, 2004 1:43 pm

The first thing I would do is get rid of the stock DP and muffler.
Then I would go for the MBC and run it up to 10psi.
After that I'd hold out for a turbo and intercooler, no point in doing just one or the other to me. You would save the pain of redoing the IC pipes because any good turbo upgrade uses the regular Subaru compressor clocking. This engine will run almost forever whithout an IC at stock or a little over levels of boost.

greg donovan · Post by **greg donovan** » Sat Nov 13, 2004 3:27 pm

BAC5.2 wrote:What is he buying?

a 2.8 A4. doesnt have time for the SS and wants to get it out of MN salt and into the hands of someone (me) who will not pull the engine out and put it in an imp or turn it into a rally car.

greg donovan · Post by **greg donovan** » Sat Nov 13, 2004 3:35 pm

-K- wrote:The first thing I would do is get rid of the stock DP and muffler.
Then I would go for the MBC and run it up to 10psi.
After that I'd hold out for a turbo and intercooler, no point in doing just one or the other to me. You would save the pain of redoing the IC pipes because any good turbo upgrade uses the regular Subaru compressor clocking. This engine will run almost forever whithout an IC at stock or a little over levels of boost.

while you make valid points i just want the security of an IC. besides the car should never have been made w/out one.

the real reason i am getting this car is that it has AWD and A/C while my current ride is FWD and no A/C and a AM/FM radio. that it just happens to ba the coolest sedan out there and is a car i have wanted ever since they came out in 91 is purely icing.

a DP would cost how much? im guessing more than a used saab IC and some piping. but who knows in the end it (the IC) could cost /same more. so i will probably not do anything but a boost gauge to get good baseline boost readings. besides the winter in ND is not the best time to be wrenching in a unheated garage.

-K- · Post by **-K-** » Sat Nov 13, 2004 6:50 pm

I can't agree more that we should have had an IC stock.
And you'll have fun moding it whatever way you chose. Even stock it put a smile on my face

greg donovan · Post by **greg donovan** » Sat Nov 13, 2004 7:06 pm

-K- wrote:I can't agree more that we should have had an IC stock.
And you'll have fun moding it whatever way you chose. Even stock it put a smile on my face

thats what im hoping. i have driven plent of 2.5 powered cars and i'm hoping the extra 30 foot pounds of torque will be more fun than the 160 in the ej25.

dzx · Post by **dzx** » Sun Nov 14, 2004 2:20 pm

As with most stuffed vehicles, the torque curve is flatter so you get more power all the time rather than a peak. So, it should feel quite a bit faster

greg donovan · Post by **greg donovan** » Sun Nov 14, 2004 2:47 pm

dzx wrote:As with most stuffed vehicles, the torque curve is flatter so you get more power all the time rather than a peak. So, it should feel quite a bit faster

i havent driven too many trubo cars. and they were not in situations where i could really "play."

one DSM that was kind of fun a supra that my friend wouldnt let me "test" and a GC8 WRX rally car but that was driven to the car wash in a city so i had to behave. something about alot of stickers and lights attracting attention.

-K- · Post by **-K-** » Mon Nov 15, 2004 12:43 pm

You'll never want to go back to N/A.....

I look at cars and I'm like, I would get bored with it no boost, even if it is faster than my car. I even want to put a turbo on my motercycle....

IronMonkeyL255 · Post by **IronMonkeyL255** » Tue Nov 16, 2004 6:45 am

greg donovan wrote:
BAC5.2 wrote:What are you doing that'll give you 35hp and 50lb-ft?
selling my 90 fwd nonturbo to my brother and buying my friends 94 SS.

I did the '94 FWD n/a wagon for '91 AWD SS mod myself.

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using an intercooler w/stock boost levels

using an intercooler w/stock boost levels