9 psi on stock compression . . .

[JoeB]

You're correct, I still haven't done anything to decrease compression from the stock 10.5:1 or beef up the bottom end and if you're wondering, yes it worries me but so far everything looks good. I don't really have a hp number. I've been doing hp tests on my G-Tech Pro Comp just to get comparisons when I make changes. I don't really care if the readings are accurate or not, I just want a base-line to compare to. -JoeB

[xtychx]

Just to jump in, joe and I were chatting about this today. His success with the 8psi seems that our stock internals might be able to handle more than meets the eye...

To give my take on the situation, im running the 7psi pulley with no water injection and on 91 octane pump gas (california :/). No knock. It would seem that the fuel system upgrade is the most important thing to have when going up in boost. The only limit I can see myself facing is my crappy octane rating, but other than that I might feel confident going higher with water injection, just like joe has.

-xtychx

[cdssolara]

I have 7 psi, also. Since I'm in CA, I also run 91 octane gas. I bought the lower compression heads from Jim@Foreign Affairs, so that's helping me get away with it. I was getting the CE light for awhile due to knock sensor issues, although the car didn't seem to be knocking. I had the knock sensor input rewired so that #2 is providing both signals to the ECU, and haven't had any problems since.

[SBCelicaGT]

There seems to be a lot of confusion in this thread. Allow me to try to clear things up.

First off. the roots-style blower that TRD provides from Magnusson makes boost by pressurizing the manifold. This will mean that an artificially high boost reading will be shown if the heads flow like crap since the air is basically just piling up in the manifold which will make the blower work harder which causes the air temp to rise. This reduces the efficiency of the system. I wouldn't be surprised at all to see your boost readings drop along with intake air temps simply from freeing up the head flow a bit, or by installing a set of headers. I'd like to see a set of blower cams developed that utilized a longer exhaust duration. I think this will help a good bit.


Assuming it's an M62 supercharger (which I think it is), it's good for about 14000rpm before it just blows hot air. See here for details:

http://www.automotive.eaton.com/pro...hargers/M62.asp

A quick measurement of my crank pulley shows it to be approximately 6.18". With a 2.20" pulley, at 6300rpm engine speed, the blower is spinning at about 18000rpm.

In fact, doing a quick tabulation:

Pulley_____Blower RPM
3.5_______11124
3.4_______11451.17647
3.3_______11798.18182
3.1_______12559.35484
3.0_______12978
2.9_______13425.51724
2.8_______13905
2.7_______14420


So then yes, the 2.2" pulley puts the blower WAY past its efficiency range.

Why is this bad? Heat. Why is heat bad? Pre-ignition. Why is Pre-ignition bad? Because it goofballs up your rods and pistons.

In other words, It's not the boost that will kill the engine, its the heat that will cause your engine to detonate. Heat melts pistons. RPMs are what destroy connecting rods. A properly tuned 1MZ should be able to handle a lot of power. Forged internals are simply a precaution to keep the engine from blowing itself to bits when it detonates.

What I'm getting at is that the engine should be able to "handle" the boost itself just fine up to a certain point.

To help combat the heat issue, I'd definitely look into water injection to spray into the air stream AFTER the blower. Water injection, or any other kind of liquid like throttle body cleaner, is EXTREMELY DETRIMENTAL to the rotor blades of the blower.

I believe he can do this with 9psi of actual boost. If he's done fuel system upgrades to support it. In cold weather, my 2.6" 7psi pulley will read as high as 10.5psi. On warm days, it reads 8.5psi. I've been running this pulley hard for a while now.

When I first got the supercharger and decided 4psi wasn't enough, I asked many places about safe levels of boost and got the familiar answer that 5.5psi was all I could do safely with pump gas. Having 94 octane available locally, I went straight to the 2.8"pulley that should be 6psi but read 7-7.5psi. I realized I needed some fuel system upgrades so went with the URD fuel system upgrade including Walbro 190lph pump, Bosch 318cc injectors and SS FTC piggy-back computer to control air/fuel and timing. Then I decided it was running so well, I could go to the 2.6" 7psi pulley that actually gave me 8.5psi. Then realized I needed to do more fuel system upgrades so I modified the fuel regulator to 59psi and added the fuel line and filter upgrade from Jim@ForeignAffairs

JoeB proves my point. On a 2.8" pulley, the air is piling up in the manifold due to the fact that it can't exit the combustion chamber fast enough. This causes for that artificial boost reading.

Upgrading the fuel system for a high boost 1MZ will definitely help combat the chances of pre-ignition, but I think to an extent, you will find that the diminishing returns are due to the flow of the engine. This is why the header/exhaust upgrade makes such a huge difference. I'll bet a set of blower cams coupled with an exhaust upgrade would make a big big difference as well.

Just some things to think about.

[cdssolara]

Good post; very interesting.

Actually, better flowing heads, as well as headers/exhaust systems have been developed by members of this community (Thanks Jim and Eric!). A number of people are using both, so hopefully the heat issues have been addressed. JoeB has also been experimenting with water injection, and seems to have had good luck with that.

[TRD_solaRa]

damn, that's alotta good input . . . i haven't been online in awhile too. anyways, all i know is that his car has been running on this daily driven for 2 1/2 years or so.

[SBCelicaGT]

Good post; very interesting.

Actually, better flowing heads, as well as headers/exhaust systems have been developed by members of this community (Thanks Jim and Eric!). A number of people are using both, so hopefully the heat issues have been addressed. JoeB has also been experimenting with water injection, and seems to have had good luck with that.

Well, as far as the heads go, it's not so much a matter of improving the head itself, as that looks to flow quite well. Typically 4 valve heads do. I think it has more to do with the camshafts. With the blower much more air is being shoved into the cylinder, but there is nothing to compensate for this on the exhaust side. Thats why I think an exhaust came with more duration(keep the same overlap though!) would be quite beneficial.

[JoeB]

SBCelicaGT, that's some good info and I enjoyed reading your points of view. I called Magnusen and they said the max rating for the supercharger was 16,000 RPM but they didn't recommend spinning it over 14,000-15,000RPMs due to the heat generation. What method did you use to measure the crank pulley? If your readings are anywhere near close (and I have no reason to think they aren't), that is exactly the problem of increasing the boost.

Regarding water injection before or after the supercharger, I don't agree. Injecting before the throttle body gives the best chance for good evaporation of the water and even distribution of the cooling. After the sc, you have much more chance of leaving water (not evaporating) and not getting an even ballance accross all cyliners. The problem with injecting before the throttle body being hard on the sc is when people run high content mixture of ethanol, alchahol or methanol. Too high of a content can actually corrode and deteriorate seals. It's been recommended to me to use a 50/50% mixture of water and methanol. I've been told a good mixture like this is even better because it keeps the parts clean (like steam cleaning). -JoeB

[SBCelicaGT]

Joe, excellent info from Magnusen. I had measured the crank pulley using a ruler which I know is not very accurate. I'd say my measurement could be off by as much as 0.2".

As for water injection, there are two main reasons why you need to inject the water after the blower:

1)Spraying before the blower will damage the rotor blades. End of story. The tolerances of the rotor blades are extremely tight and are coated. Since water is incompressible, it becomes superheated when the rotor attempts to compress it and will cook off the coating and create hot spots. These hot spots cause further coating damage which results in a blower that does not make boost as well.

2)From a thermodynamic standpoint it makes sense to spray after the blower. Water injection cools by energy conversion. The heated air transfers energy into the water which converts it into a vapor. Due to this fact, if you spray before the blower you are going to waste water since it will stick to the insides of the rotor, throttle body, and intake.

Also due to thermodynamics, it does not matter whether the vapor is dispersed completely since the entire plenum full of air will change in temperature which is what you want.

Think of it like an intercooler for a turbo. Would you install the intercooler before the turbo heats up the air?

Hope this helps.

[JoeB]

From a common sense standpoint, I agree with you 100%. My first thought after questionable improvement injecting before the throttle body was to move the spray to the sc housing. After consulting a couple pros and Magnusen themselves, I finally conceded my common sense wasn't going to cut it.

I still like what you said though and don't want to give up on it. The intake air isn't really heated until it is compressed by the sc. So 2 things, I don't think it will cause any problems on the rotor blades, more importantly though like you said, most of the water is gone before it gets to really cool the charge. Where exactly would you inject the water? If you could illustrate on a pic of the sc housing, that would help. -JoeB

[xtychx]

Joe,

There is a perfect tap parallel to the boost tap on the top of the manifold, right past the supercharger housing. I was over at Adrians (SBCelicaGT) house the other day and we were talking about the water injection issue and we completely agree. Shooting the water into the intake makes no sense. The best method would be to tap the port on the top of the manifold and shoot the water directly in so that it gets completely atomized by the intense heat.

-xtychx

[SBCelicaGT]

Joe, I promise you that anything injected into the rotor will screw it up. I work for Jackson Racing/ Moss Motors and I've had extended discussions with our tech who corresponds with the engineers over at Magnusen regarding warranty issues.

As for a location, I think that flat point on the top of the housing would be the easiest location. The hardest part would be keeping the metal shavings from falling into the housing itself.

[JoeB]

I think I remember the spot you are referring to. It's a small flat circle on the top of the sc. Unfortunately I can't get to my car to see it now but isn't it under the strut bar? As far as the metal shavings, I would just pull the sc off to do it. -JoeB

[2002greenhornet]

I'm late to this party, but I want to thank you guys for this incredible info. This kind of cerebral discourse is difficult to find.

I'm on the edge of adding a blower, and considering the 6lb pulley, so it's really comforting to get detailed analysis of the processes involved and how best to optimize the result. What I'm getting from this discussion is that it's best to wait on the 6lb pulley until I am prepared to spend the money on the headers to better aspirate the engine at boost. Is this correct? Or is it safe to add the pulley if I upgrade the fuel delivery with an eye to adding headers later?

I'm not interested in adding water injection, and really modding to the max, I just want to get a little more of what I know this motor is capable of without spending too much time tuning. My wife already thinks I'm crazy just by lowering the thing!

(Incidentally, JoeB, we are practically neighbors. I've met Rizal, and my sister lives up in Middletown. I look forward to meeting you one day.)

[JoeB]

Steve, the order I did it and I think works well is first the intake but realistically could come at any time before a dyno tune. Then the blower and keep it at the stock 4psi. Then add an EMS to control the fuel. Then headers, 6psi pulley and dyno tune at the same time. I hope you can make it to the picnic we are having at Great Falls in October - see the Events section. I'm looking forward to meeting you. -JoeB