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Intercooler heatsoak, and peak boost lower.......

Well, after being stuck in traffic for 15mins, and the rad fan kicking in, then getting free onto a nice dual carriageway, I noticed the boost gauge isn't boosting quite so high as it was 2 weeks ago.

Now for those not in the UK, we have had a particularly mild last couple of weeks with temps far higher than normal.

This morning, same dual carriageway, nice normal engine temps with the needle in the lower third of green (never normally goes much above that), I noticed that the boost is still not peaking quite so high, and dropping back slightly more (nowhere near baseboost level though). I'm guessing that the warmer less dense air is causing the APC and knock sensor to back off the boost with the warmer less dense charge going in.

Now I don't have the money or time to perfect a decent water injection system, and I'm already running Shell Optimax (cheapest super locally ATM), so I'm guessing if it still knocking (or getting backed off pre- knocking) I need to cool the intercooler/inlet charge.

I'm considering an intercooler fan on my original side mounted all alloy IC (can't really go the FMIC route on a flat front without some butchery). Has anyone done this?

Was thinking something small like a Fiat 127 Rad fan (puller fan if possible to avoid dismantiling the original IC to fit it.

Was thinking basing the operation on either a VAC/Boost switch, or on temp sensor in the inlet pipe, post IC, so it will trigger if the temps get above a certain level as they exit the IC.

Apart from a cone filter, and alloy recirc valves and replaced vac hoses, the engine is pretty much standard, haven't tweaked the APC yet, and if I'm losing boost in spring temps, I hate to think what will happen mid summer on the few scorching days we get in the UK.

Any experience anyone?

Reply to
MeatballTurbo
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During the colder weather, boost peak was on the edge of red, dropping back only a little.

Yesterday, it was peaking at 3/4 yellow, dropping back to 2/3rd yellow. Plugs were changed in the last 8k miles, had an oil and filter change 3 weeks ago, airfilter is clean. Leads haven't been changed, but there was no signs outwardly of them cracking. changed the rotor and cap about 8-

9k ago just before I did the plugs.
Reply to
MeatballTurbo

Water spray onto the intercooler works well. Screenwash pump, water tank in the n/s wing area, button on the dash and a couple of fine jets aimed at the IC. Water has a high latent heat, and will remove large amounts of heat from the IC at the press of a button.

Not tried a fan, but I'm sure that would help even more.

I've definitely experienced power reduction on hot days, but can't say I've noticed much in the last couple of weeks. Are you sure everything else is up to scratch? Plugs etc? I run normal unleaded, and boost easily peaks at 11.5psi on the untweaked T16.

Reply to
Grunff

Should be. Timing chain was changed about 5 months ago, so they should have checked the cam and ignition timin when they put everything back together.

When the rad fan kicked in yesterday, on the way home, and stationary for a while, before the temp fully dropped, it was peaking at 3/4 and dropping to half, even bigger peak dip, and even bigger drop between peak and stable. But after a while driving, yesterday, and this morning, it was pretty close to what I'm getting now.

Reply to
MeatballTurbo

That's a big difference for such a small temp difference I think. Is your timing spot on?

Reply to
Grunff

And the cam chain was done before I get the best boost over the winter.

Reply to
MeatballTurbo

Hmmm.

Reply to
Grunff

Has a cone filter, but it gets it's feed directly into it's heatshield from the standard funnel.

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Mind you, if the connection from the intake funnel to the heatshield has come loose, then it might make quite a difference.

Guess when I check the oil over the weekend, I check for loose vac pipes, and see if the intake system is still intact.

Good thinking that man.

Reply to
MeatballTurbo

Sounds like your car is particularly heat sensitive. I wonder why. You haven't got a filter pulling in air from the engine bay, have you?

I've not experienced this level of temperature sensitivity on either of my T16s.

Reply to
Grunff

Ye, do check that. Something ain't quite right methinks.

Reply to
Grunff

And if the motorway is clear tonight, I'll give it a damned good push in

3rd and 4th and see how well it boosts in clear air with good flow, and not over warm.
Reply to
MeatballTurbo

Reply to
saabtech

Please disregard most of the above ramble, having thought about it on the way home, The post should read like this: If you bypass the apc solenoid by joining the hose from the wastegate acctuator and the turbo housing together and plugging the hose to the air pipe and normal boost is returned, then you know that the apc is controlling the boost for some reason, If normal boost is not returned then the fault is with the base line boost, eg: wastegate diagphram etc, It is also a good opportunity to check that the base line boost is correct, ie: just before or on the red on the boost gauge. Hpoe that makes more sense, Regards, Tom, having had a hard week.

Reply to
saabtech

In article , snipped-for-privacy@btconnect.com spouted forth into alt.autos.saab...

Cheers Tom. Will check that out.

Reply to
MeatballTurbo

In article , snipped-for-privacy@btconnect.com spouted forth into alt.autos.saab...

BTW Tom, Boosts slightly higher in 5th than 3rd and 4th, but I think it has always been that way.

Reply to
MeatballTurbo

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