Heat soak

[hytorksc]

Does the SC lose more torque than an N/A car when it's very hot outside?

Does the low 8.2:1 compression combined with the inefficiency of the m90 have something to do with why the SC bogs so badly in very hot weather?

Would an LS1 car or a m3 BMW lose more power than ours in hot weather (or is it the same or better)?

[DamonSlowpokeBaumann]

If you have 8.2:1 compression.....The SCwill lose a substantial amount of power when hot ..Barley any air flows over the IC...Get an IC Fan..Cant hurt

[hytorksc]

thanks damon,

i already have an IC fan for my stock IC, but i took it off because the fan was worn out. I didn't feel much of a difference with it on to tell the truth.

I guess there is no other way to counteract the bogging. A bigger IC would really help this out i guess.

[hytorksc]

i wonder if anyone here has thought about increasing the compression on the 3.8 especially since now we have the cooler (temp) whipple to work with. There are going to be lots of new possibilities with this new supercharger type.

[David Neibert]

The lower compression will actually work better with the whipple or AR. If you want more power, there are lots of things you can do that will make the car run strong even if it's 90 degrees outside.

After having done my mods over and over again, I think ported heads and a bigger cam are the place to start. Then all your other mods will respond much better.

David

[Deep6]

I don't know if anyone knows this, but the 89-93 SC's has a 8.2:1 CR and the 94-95 engines have a 8.4:1 CR.

Could an owner run a 9.0:1 CR with a whipple pushing like 20psi????

[hytorksc]

when i'm ready, i think i will take dave neibert's suggestion and also try shaving down the heads a little. This shouldn't bump up the compression too much i would think (in context of the whipple), and especially since my goal is to stay around 300-400 rwhp range anyway... less chance for something to break.
What i really want to do is swap the aod for the m5r2 for much more power (gear leverage) to the wheels, and do the exhaust/heads/whipple install thing. if i put alot of attention on the IC (install a bigger one), re-route the ic tubes away from the headers, eliminate the bottleneck at the return plenum/intake manifold, do the heads and shave them down a little for more compression, add the whipple, and install a fairly large full exhaust (not too big for optimal scavenging/loss of low end torque), i think this would be the dominating street car i've been looking for. this should put mine above 350 rwhp with unreal torque down low which is in excess for a daily driver. if i was racing at the track like most of you seem to be, i would keep the aod (upgraded) and build the motor up much higher. of course if i can get more power out of it for the street i will do it to the max. hopefully very little or no bogging either.

[David Neibert]

On a forced induction motor, low compression is a good thing. It allows you to run higher boost and more ignition timing with lower octane fuel, without detonation.

The whipple is effecient enough to produce higher boost without pulling nearly as much power off the crank pulley, so you want the low compression to take advantage of the higher boost. If you just raise the compression, it won't do much except get you into the knock sensor that much sooner.

David

PS: I have stock 8.2:1 compression.

[DamonSlowpokeBaumann]

I bumped my compression a lil bit with my new motor and used thermal barrier coating on the pistons and combustion chambers to ward off detonation. If you ever plan on building a new bottom end that wouldnt be a bad idea...You can also hook up some kind of water mister to your IC...Believe it or not that works..Alcohol works even better(however it corrodes aluminum)..Just idea for you to work with while using stock IC.

[hytorksc]

thanks guys. the water spray idea sounds good. it would be kinda nice if i could rig it to automatically spray in intervals whenever the IC gets over a certain temperature on very hot days. i'd have to experiment with that one as usual.

[BT Motorsports]

I am going to give an opposite approach regarding compression and David's statement. A higher compression engine will require less supercharger (in terms of volume) to produce the same horsepower. Before jumping down my throat, let me expand on this a bit. The higher the compression (to a point of course), the better the n/a qualities your engine will have. Drivability improves further with this approach. The reduced need for higher boost and additional timing (to a point, you can go below the supercharger's peak effeciency level of course) lower combustion temperatures as well. Additionally, there is a lower demand for higher octane fuel. This is important more so for the west and some of the midwestern states that do not typically offer over 91 at the pump.
The lower outlet temp of the supercharger results in less need for a highly efficient intercooler system and better power stability as well. One thing you will find is that you can never have to much intercooling capacity. Remember, heat is energy, just in our case, in an unusable form. In a turbo system, the turbo takes advantage of heat with higher exhaust gas velocity aiding the turbo to spool faster, our blowers do not take advantage of this.
All in all, the more efficient your normally aspirated engine is, the less work it takes to make more horsepower when you are forced induction. If you increase the normally aspirated qualities of the SC engine off boost via higher compression, you will not have to spin the supercharger as fast or use a larger supercharger to acheive the same results. The M90 has been getting a bad rap lately for having poor efficiency and no top end, however, its the total sum of the combination of parts used that are really causing this. Build a higher compression engine and spin the M90 slower and you can still have your low end torque while making peak HP up to and beyond 6k RPM like Anthony Rongo recently showed us the whipple can do.

[BT Motorsports]

This chart should help out a bit with a visual comparison:
http://www.BlueTongueMotorsports.com/misc/boost_vs_comp_ratio.jpg

Paul

[David Neibert]

Paul,

That all sounds great and logical, but for some reason it doesn't work like that. I'm not saying you can't get good power with higher compression, I'm just saying you can get more with the lower compression. This is especially true if you have the means of making more boost without consuming and equal amount of power off the crank shaft, such as when using a twin screw blower or a turbocharger.

I'm in the same boat with the 347 turbo project, because the engine ended up with 9.3:1 compression instead of the 8.6:1 I speced. Because of the higher compression, I'm expecting to make about 50 rwhp less than I would have on 93 octane. Some of the quickest/fastest turbo and supercharged cars out there are running 7.9:1 to 8.2:1 static compression.

David

[BT Motorsports]

Unfortunately David, your comparison is not fair for this discussion due to the properties of a turbo system vs roots or screw system. There are many other factors of engine dynamics that play a role in this (such as combustion chamber design, valve timing etc) which I am not introducing into the conversation or we would easily get lost in the technical aspects instead of addressing this gentleman's thread.
When you take the instance that the motor in question has exceeded the supercharger's capacity to deliver unless you turn it well beyond its efficiency range, your parasitic losses go through the roof resulting in much higher hp loss to turn the supercharger, higher outlet temps and greater chance for heat soak. In the example presented, a higher compression will reduce the amount of power needed to turn the supercharger, reduce outlet temperatures and reduce ignition timing. All of these factors with the same final compression ratio add up to a better combination.
If you look over the chart you will see a difference of 1/2 point compression(8.5@16psi vs 9.0@14psi) means yeilding nearly a 2psi offset. Take into account the amount of additional speed it takes for you to turn your M90 on your particular engine in this example. Next, consider what higher compression would do in reducing your outlet temps and crank hp needed to turn the blower since you can acheive the same final compression ratio at a slower speed. The lack of additional RPM, intercooling capacity to avoid heat soak or keep outlet temps in check and the reduced timing needed and you can see where the gains are.
My point, simply that higher compression in this example can give the man what he wants without giving up any HP and keep his wallet a bit heavier all while running the same octane fuel.
HytorkSC, where are you located and what fuel do you have available to you? With all this discussion, no one has addressed the chance of detonation or the knock sensor pulling timing back as a possible reason for your power loss.

Of course, regardless of compression and induction choices, there comes a limit where you reach the peak cylinder pressure an engine can handle and it breaks. The key is to improve efficiency rather than finding that limit, othewise, displacement becomes the only solution to more power.

[Rich Thomson]

Does the SC lose more torque than an N/A car when it's very hot outside?

Does the low 8.2:1 compression combined with the inefficiency of the m90 have something to do with why the SC bogs so badly in very hot weather?

Would an LS1 car or a m3 BMW lose more power than ours in hot weather (or is it the same or better)?

Loss of hp and torque is because of the EEC calibration which is designed to prevent detonation. The EEC has tables which adds or removes timing based on ACT (air charge temp) and ECT (engine coolant temp). TPS voltage determins if the car goes into WOT. Voltage at 2.44144 and above is considered WOT.

WOT_VOLTAGE 2.44144 # TPS Voltage

WOT_ADVANCE_VS_ECT # WOT spark adder based on Coolant Temp.
( 254, -3 ) ( 230, -3 ) ( 216, -2 )
( 200, 0 ) ( 150, 0 ) ( 100, 4 )
( -256, 4 )


WOT_ADVANCE_VS_ACT # WOT spark adder based on intercooler outlet Temp.
( 254, -8 ) ( 180, -8 ) ( 120, 0 )
( -256, 0 ) ( -256, 0 ) ( -256, 0 )
( -256, 0 )


Once your ACT hits 180 degrees it pulls 8 degrees of timing out.
Once your ECT hits 216 degrees it pulls 2 degrees of timing out.

If the ECT and ACT are both pulling timing out it pulls the one with the most timing out. If your ACT is 150 and your ECT is 216 it pulls 2 degrees of timing out. But if your ACT is 180 and your ECT is 216 then you loose 8 degrees of timing.

The reason you feel more power when the car is cold is the ECT table. Until 150 degrees ECT the engine gets an additional 4 degrees of timing.

Yes all manufacturers have simular tables in the ECU designed to adjust timing based on ACT and ECT temps.

[Micahdogg]

Getting back to the original question...yes you can run higher than 8.2:1 on a supercharged engine like ours. But as David said, you will be limited to the amount of boost/ignition you can run before experiencing detonation. I seem to recall Fred running almost 9:1 on his 4.3L.

And as for your modifications...if you want a combo that will be "safer" I would not start with the heads/cam as David suggested. These mods will allow you to see better power from all the other bolt ons, but heads/cam will also require you to a higher rpm. A whipple bolted onto a somewhat stock SC motor would put you over 300RWHP and probably keep you from revving over 5000 rpm. Some of the big cams out there make power up past 5500 and keep pulling over 6000 rpm. And higher revs are most certainly harder on an engine.

Micah

[hytorksc]

btmotorsports-
HytorkSC, where are you located and what fuel do you have available to you? With all this discussion, no one has addressed the chance of detonation or the knock sensor pulling timing back as a possible reason for your power loss.

BT,

i'm in the maryland area which is right now seeing outside temps around 90. we have 93 octane down here. There is absolutely no detonation happening right now, but the answer Rich gave sounds more like what's happening to mine. it's a combo of things, especially since i have a 5% od, ported m90, and stock everything else pretty much. at lunch time today, i played around with the TPS and that seemed to help alot in the bogging dept. it's about 90 outside right now, and i'm running a 180 thermostat- the engine is still going to heat soak in traffic and slow down noticeably. maybe not as bad since i advanced the tps slightly. i'm not sure if my knock sensor is kicking in or not, the car is still fast and responsive except when it soaks in very slow traffic (rush hour).



micahdogg-
A whipple bolted onto a somewhat stock SC motor would put you over 300RWHP and probably keep you from revving over 5000 rpm. Some of the big cams out there make power up past 5500 and keep pulling over 6000 rpm. And higher revs are most certainly harder on an engine.

Micah,

But would a stock cam and heads produce 300 rwhp up high like that with a whipple? wouldn't power fall off above 4000 with stock cam/heads? i'd rather it peak out above 300 around 5000 rpm and still lay the power down at low rpms. this would give me the leverage at the wheels i'm looking for especially with the m5r2. i would think that this would still be in a safe range for the 3.8.
But i also understand that the whipple is so efficient that maybe i will get what i'm looking for by just adding the whipple itself, IC, and exhaust- who knows?

[tim]

NO!! NO! NO!! I made the big mistake of running too much compression. Now i can only run a 5% pulley and 11.5 lbs of boost and a cut in timing.

[BT Motorsports]

and i'm running a 180 thermostat
But are you taking advantage of that tstat by turning your low and high speed fans on sooner? You can have detonation occuring which is triggering the knock sensor and not know it, especially if you are running that tstat and stock fan settings. I didnt notice a list of your mods anywhere, so we are somewhat shooting at this blind, though Rich does make a very good point which will apply if your car is running hot enough to pull that much timing.

Paul

[hytorksc]

BT,

i've rigged my fan to stay on all the time. but it is an aftermarket fan which i think doesn't flow very well (1,200 cfms). i think the minimum cooling fan specs for a v6 is 2000 cfms- of course i didn't know that at the time i bought the fan. now that i think about it thats probably one of the biggest problems i'm having. it's not cooling enough when sitting still in traffic.

oh, and these are my mods- some are custom, very basic list;

*removed silencer
*k&n panel filter w- enlarged stock air box
*custom 3" intake tubing (stock one works better for velocity- better response in the mids)
*modified stock MAF (took the c&L off due to excessive detonation, bored out stock maf works waay better)
*relocated and grounded DIS to firewall (much cooler area)
*180 thermostat
*70mm TB
*port matched inlet plenum
*custom max ported m90, inlet and outlet
*mp raised top (even bored this out a little more)
*port matched return plenum to intake manifold
*iridium spark plugs
*underdrive pulleys
*5% od pulley
*bored out exhaust collectors
*reduced voltage bias on maf by modifying the circuit to add a little fuel (seems to compensate for lean mixture during part throttle caused by boring out the stock maf)- i don't know what this mod does exactly, but my driveability and throttle response is a whole lot better, and my gas mileage has increased since i did this.

like i said, my sc seems to perform consistent (can do wheelspins up to 30-35 mph from a standstill now) as long as it's not heat soaked. when it's soaked, it does more like a chirp from standstill (if that), and it bogs all the way up (sounds like timing was pulled doesn't it?). when its very cold outside, the car feels like it has 350+ hp- torque goes way up in the cold. if i was to dyno it, i think it only puts out 200 to the wheels at best. it starts and idles smoothly ALL THE TIME, no issues with part throttle response or driveability.

[David Neibert]

I think you need to get a bigger fan. BTW, how high is the coolant temp getting ?

David

[hytorksc]

D. Neibert,

the temp usually climbs and levels off just before the "N", but when it gets soaked it's on the "R" and sometimes the "M". i dont know what the actual temp is, i would guess its at 220 when it hits M.

[David Neibert]

If mine gets that high it runs like crap too, get a bigger fan or an aluminum radiator.

David

[DamonSlowpokeBaumann]

The first thing any ford engineer will say is dont screw with the stock mass air meter!!!:O)

And if you coat the combustion chambers and pistons with the SWAINTECh coatings...You can definately run the higher compression without any added chance of detonation...Run some EVans coolant and youll be doing even better!

[DamonSlowpokeBaumann]

Dave on race cars they run lower compressions to run extremely higher boost levels,,You lose drivability with lower compression levels.

My v8 Turbo motor is 9.3:1 and I'm making 7 and change to the wheels..This is with a 306

[hytorksc]

damon,

i haven't built engines before but i'm trying to take an intelligent guess here... maybe it's the fact that your boosted 306 v8 has enough internal volume to properly handle the 9.3:1 without detonation. i would think that as you get bigger in displacement, the less chance there is for detonation to occur on a somewhat tuned boosted engine with 93 octane- and you would be able to run slightly higher compression ratio. i don't know- i'm guessing that with the 232 cu in v6 on the SC that maybe there is not enough volume to run that much compression and run high boost without detonation on pump gas.

[David Neibert]

My v8 Turbo motor is 9.3:1 and I'm making 7 and change to the wheels..This is with a 306

Damon,

I'm glad to hear that you have the same compression as my new engine does, who knows maybe I'll reach that 800 rwhp goal after all.

David

PS: What does 700 rwhp feel like ??

[Randy N Connie]

Its the proper shaped combustion chamber shape,that counts.
And timing.

Randy

[hytorksc]

damon,

that maf electronics mod i did seems to work fine for me. i've been running it like this for quite a while. as far as what ford engineers think, i don't think they know everything- i mean when they design a component for the car they don't have enough insight to know how the car would perform under all conditions. i may not fully understand what their design philosophies were with the maf, but i do understand enough of the basics of how the maf works and how the computer interprets it's signal (transfer function). Before anyone criticizes me consider this... when you guys bolt on any mods, pretty much all stock calibrations go out the window anyway.

the point is the electronic mods i do are so conservative and slight that it's off the radar for throwing other sensors or EEC settings off in a major way (like going outside of HEGO circuit parameters throwing CEL's). if you understand how all the sensors work and how they interact with each other, it is possible to trim them out to "sharpen" the calibration and improve response and driveability. none of these mods will make the car significantly faster, but what i did has eliminated all of the usual running quirks that some of you are still experiencing. like i said, my SC runs about 98% to perfection idle-wise, and it starts up every time on the first try- just a couple of turnovers, and settles into a nice smooth idle ALL THE TIME in all weather conditions. no burping, studdering, roughness after leaving it for a few minutes, no hesitations, very responsive, and NO detonation (maybe a little on very cold days). and to top this off mine has 178k miles with original HG's, i have been driving it to work 140 miles round trip every work day for the past 2 years, and i briefly do WOT at 15 psi least once everyday. i'm just annoyed with the bogging during heat soak, and i am running into front end suspension problems which i'd better address soon.