I'm just curious how many people are running blowers with no intercoolers. Im looking at a V3 vortech kit, supposedly good for 7-9 lbs. What does IAT temps look like? is it even worth doing without a intercooler?

 

It depends on what your engine is making naturally aspirated prior to that 7-9 psi you're shooting for. A cast assembly can only take so much, as can a forged assembly. High IAT's will obviously weaken the rolling assembly, but there is of course a tolerance depending on what you're running. It's not unheard of to see "hot air" Grand Nationals running deep into the 11's on a factory cast setup, and it has nothing to do with it being a V6, no magic to that engine, it's based on weight and horsepower not to mention state of tune, so you need to ask yourself how much power you're looking to make at those higher IAT's, and if it's feasible with your particular setup. Asking others won't help much because every engine is different, as are individual tunes. I can tell you that a 400 horsepower hot air LC2 engine will generate much higher IAT's over a SBC making the same power running a V3 supercharger due to the latter's reduced restriction in the exhaust, as well as the compensating torque itself, so if this is your target, then keep your timing and fueling where it needs to be, and you'll be fine.

 

Im running a GM crate engine, The 350 HO. Vortec heads and mild cam. I will be keeping the tune very conservative as its a street car.

 

I don't see too much of a problem, based on the flywheel horsepower of those engines, if I remember correctly around 330-FWHP, you are looking at approximately 495-FWHP at 7-8 psi, call it at a rounded 400-RWHP on a good day. Just be sure to run quality fuel at the pump, and keep timing conservative. Boost is very linear with a centrifugal supercharger compared to a turbo, so IAT's should be much lower in comparison with a hot air setup making the same power. E85 is recommended if you decide to go with more timing running no inter-cooler...

 

With the vortec's i only run 32* max N/A I figure being safe ill take off 2-3* per PSI. Ill probably run a intercooler eventuially, but i wanna do a efficient one if i do it. Just running out of money fast. Im running a external walbro 255.

 

I'm running a torqstorm centrifigual supercharger with no FMIC and I run meth/water injection in a 5.3LS. Put 40miles on the combo and in fair weather like 60-75*F my IATS have been 147-150*F at almost 8psi but only turning 4400rpms. Meth wasn't engaged yet but to be 75-90*F above ambient with low humidy is not great. I ordered a cheap FMIC and going to try to fit it into my TA to help with NA and low boost IAT temps, supplemented with my water/methionine higher boost levels.

Torqstorm said it was common to have IAT temps in the 170 range and from what I hear positive displacement type supercharger a have high IAT temps as well.

In short you only want to be 10-30*F over ambient. If u can run one I would suggest it being im now going to try to make one fit.

 

Which trim? S? si?

-- Joe

 

Si

 

I see, or atleast water/meth setup.

 

Yea, water/meth at minimum if your over 6psi. Really depends on your IAT temps.

 

We will see, Blower should be here monday/tuesday

 

You'll see alot of heat after driving around for awhile. The charge piping and blower will heat soak a good 140-150 deg easily and see high iats in wot

On a track pass with cool piping after sitting for awhile, it could live.

But i would do a meth water injection kit at the very minimal

My remote turbo car on 9 psi would still see 150 deg on short pulls. Thats alot on pump gas, i would cool it down if i were you. I have been as high as 170 deg in boost on pump gas but would not recommend it

 

Summit racing says their good for 5-6 PSI, while on the website says its good for 7-9. I wonder why they even offer them without intercoolers if detonation is almost guaranteed? Every foxbody i see doesnt run a IC

 

Its not guarenteed, but you need to be aware of the increased chances. The tune has to account for it and if you dont use a boost referenced efi system then you really have no tune safety to compensate for high iat

 

Im running MS2, so my spark table will be modified. Wonder if i should lower the MAT timing retard table so it pulls a couple of degrees when it gets hot(140+). Im just not sure how fast the GM IAT sensors react

 

Like I was saying in another thread, I ran a S-trim on a iron headed 355 for a couple of years and made 565hp. I'd have to look at my datalogs, but it was 14+ psi. Non-intercooled.

I did blow it up eventually, but it was by being stupid and not having enough fuel. The injectors went static around 5800, and I'd try to shift around 6000-6200. AFR leaned out after 5800 or so, which actually made a little more power. Ran it hard in 80+ degree weather. What killed it was a night in the low 40s/high 30s in October. Apparently it leaned out a little too much that night.

-- Joe

 

I'm using a toyota IAT sensor with my megasquirt. Responds fast. Wells # SU343. In the intake tube before throttle body.

Yes, pull timing if it gets hot.

-- Joe

 

Yeah i dont think ill be anywhere near 14 lbs or 6200 RPM. What temp do you think i should start at joe?

 

175 degrees I start a ramp down from 1 degree advance to 4 degrees at 250f.

Quickly looking at my logs, when NOT running an intercooler I never saw more than 180f with the S-trim.

-- Joe

 

and thats on top of pulling timing on the table correct? First 4 psi i got it pulling 1 deg per psi, first 8 it pulls 2 deg per psi

 

I don't do it that way, but many do.

If you compare back to back runs with EGT, you'll notice your exhaust temps are hotter when you retard timing under boost.

So for the past 12 years or so, I've just locked my advance out after a certain RPM vs map.

If you log your car doing some WOT runs, you'll find that your not using most of your advance table anyway. Better to just lock the advance at 2500 rpm or so from the 90kpa column all the way out, then use the mat correction table as a safety net.

Turbo car might be a little different, I didn't own one long enough to get too invested in the tuning, but a supercharger has a predictable boost curve.


-- Joe

 

usually 5-6psi doesnt require a IC. Thats how the kits are marketed, 5-6psi is pretty tame. Besides timing and fuel you should be fine but I would be looking at the IAT temps either way. Your not going to have an negative affect on the setup by running a IC or meth, but at 5-6psi your not required too. Cooled 4psi would make more power than hot 6psi, meth has no pressure drop but you have to tune it in. 70/30 could richen you up .5:1 on AFR. With the GM PCM the IAT isn't quick enough as a fail safe for meth activation but i have it pulling timing at 130*F at 1* and then goes up after that. Originally my IAT adance was -4* at 140*F (stock tune table) and only had 13* advance at 7-8psi but at 147*F IAT temps. I run 93 pump and thats high temps for pump gas.

If you want easy, run a meth kit, wiper fluid, pressure Hobbs switch set to desired PSI, size the nozzle for HP level and run a safe tune timing wise without meth (compensate for AFR with meth on) and then have high IAT temps pull timing if they stay up.

 

Some good stuff guys! Thanks! Ill post the timing table i have set up for now, when i get a second. I think i have 12* at 8PSI@ 4500RPM, and it tapers down lower advance in the lower RPM range. Ive heard from quite a few people that the GM IAT's arnt fast reacting, so maybe ill see if i can find that toyota IAT sensor. I want to run a FMIC, im just on the limit of my budget this year. I have a few volvo intercoolers kicking around at work, Maybe ill see if i can stuff one in the front. Ill stack IAT timing retard on top as a safety net.

 

Open to feedback - 4, 8 and 12PSI