7 replies to this topic

[coopertrooper2001]

I am running a VMAX charger on my MPI complete with oil cooler, re-cored VMAX radiator and fan and a charge cooler (water jacket around the charger - linked to an external radiator.

I can only do about 60 MPH over the course of a 30 mile motorway journey before it starts to get close to 3/4 on the temp guage.

What are people doing to combat the heat issue?

[Wil_h]

Out interest what boost do you run (I think 10, do you have a bost gauge?) and what pulley ratio do you run?

I'm trying to work out where all the heal is coming from ijn the first place. I already know, but I'm interested to do some calculations for you.

[smith1380gt]

I would have a look at your ignition timing and distributor advance curve. Might be too advanced- which will create exess heat- have you had it rolling road setup?

I have a VMAX supercharged 1275, 2 core super cool rad, NO OIL COOLER, and often drive over 80MPH on the motorway with no temperature issue at all. I don't have the supercharger cooler either.

You might also check that your fan is on the right way around, which is easy to do, and a common mistake which will cause overheating. My car rarely gets over 180 C even on 25C days.

[Boomboy77]

I would have a look at your ignition timing and distributor advance curve. Might be too advanced- which will create exess heat- have you had it rolling road setup?

I have a VMAX supercharged 1275, 2 core super cool rad, NO OIL COOLER, and often drive over 80MPH on the motorway with no temperature issue at all. I don't have the supercharger cooler either.

You might also check that your fan is on the right way around, which is easy to do, and a common mistake which will cause overheating. My car rarely gets over 180 C even on 25C days.

Its an MPI, it wont have a dizzy and the fan is electric. But I think you may well be along the right lines, is either running weak or too far advanced.
I think the vmax pulley works out at 1.8:1

[Turbo Phil]

Are you using a decent temp gauge, or just the standard "guessometer" ?

[Wil_h]

1.8:1 is interesting. By my calculations this is pumping more air than needed for 8psi on a 1275 engine, 9000rpm is more like it. However, the massive amounts of heat the M45 is making must make the charge so hot that the pressure is reduced somewhat, meaning it needs to be run 'overspeed' to compensate.

If this is the case all you can do is add extra fuel on cruise to cool it down. Other than that, reducung the SC speed will help. I would be interested to know how power is affected if 1.5:1 ratio pulleys are fitted.

[mininutter]

1.8:1 is interesting. By my calculations this is pumping more air than needed for 8psi on a 1275 engine, 9000rpm is more like it. However, the massive amounts of heat the M45 is making must make the charge so hot that the pressure is reduced somewhat, meaning it needs to be run 'overspeed' to compensate.

If this is the case all you can do is add extra fuel on cruise to cool it down. Other than that, reducung the SC speed will help. I would be interested to know how power is affected if 1.5:1 ratio pulleys are fitted.

Hi Wil, would be interested to see your calculations.

Just saving up to buy materials to make up a charge cooler sandwich plate.

Should be buying the materials later this month, I've my work place machine shop to abuse in my lunch breaks )

[coopertrooper2001]

The charger has been modified (standard pully) to run a little more than normal boost - it is somehow restricted by some changes Stuart makes. I dont know what level of boost it runs exactly.

I am running the standard guess-o-meter, but with the laptop plugged in you can read the temp in degrees C. I will post up some values when I get the laptop connecting properly. From memory above the normal line on the guage is about 92 degrees and half way between normal and max is 95-98. I think this is too hot!