I have a ZZ1 crate motor...forged crank, forged rods, hyper pistons (atleast for now). The engine has 9.8:1 compression and has only 5K miles on it.

Just got my hands on a Paxton SN92. Plan to run the stock sized pullies but don't have the entire kit so its going to be a custom install.

Although the engine is carbed right now, and rated at 345 hp from GM as such, I plan to run a TPI system on it which will be siamesed.

Although the compression is 9.8:1, a thicker but high quality set of head gaskets could bring me down to a more reasonable 9.5 or 9.3

My question is? With water/alky injection and this much boost, 5-6 lbs, am i going to need a BTM? I will install a walboro 255 high pressure intank pump because i need a EFI pump anyways but will i need an FMU to run this system or will the alcohol injection be enough to offset the possible lack of fuel. What injector size would you recommend running, 30lbs? I do have an adjustable FPR. Do i even need to lower the compression with the water/alky injection?

Thank you so much for your time if you could help me out. Anyone else is more than welcome to give me their opinions as well I just posted for Willie because i know he has a lot of experience in this.

 

First and foremost, timing should be addressed. You need to determine best total timing at WOT. On a normally aspirated engine, you want total timing to be 36 - 38 degrees. On a supercharged engine, there are two avenues: 1) Retard timing under boost to aid in preventing detonation or 2) Retain full timing and use water injection.

The sole purpose of water/alcohol injection is to eliminate detonation (knock) by reducing in-cylinder temperatures. Detonation can also be addressed by retarding timing. So which is the better solution? The answer is obvious. Retarding timing will result in a power loss in any engine, whether it be supercharged or normally aspirated. Using water/alcohol will allow full ignition timing, as well as "steam cleaning" the carbon build-up in the cylinders. You should have been my 305 upon disassembly at 109,000 miles. I could not believe what I saw, or what I didn't see. The pistons looked new!!

For further information on water/alcohol injection, do a search on the Forced Induction board at camaroz28.com. Look for Rich Krause's posts (a.k.a. rskrause). He's an M.D., a gearhead and very intelligent!! He owns a daily driven 700hp supercharged (& nitrous injected) Camaro. He is very knowledgeable on water injection and has further insight. He also uses the Superfueler for additional fuel, no FMU (just like me). Note: I will never use an FMU as it is the cheapest, most non-user friendly method of fuel management I've ever seen. It's fuel enrichment curve is linear -- not adjustable which is terrrible. Rich will agree with me here.

In your case with "only" 5-6 psig boost, I feel you will probably benefit with water/alcohol with no additional supplemental fuel system.

Unfortunately, sizing injectors is NOT a science. There are tables to determine size by horsepower ranges, but I find it's more trial and error. Take your best guess on what size you think you'll need. For starters, ask others with a similar setup and see what they use. But keep in mind that you might have to go smaller or larger.

Hope this helps. If you have further questions, ask away and I'll try to help.

 

Thank you for that info...Would you lower the compression from 9.8 with a thicker set of head gaskets or leave it as is?

 

I feel 9.6 is the limit for 91 octane with no detonation on a normally aspirated engine. This is important point, even on a supercharged engine because it is not under boost the majority of the time. The reason why LT1's can run 10.5 C.R. is because they are reverse cooled -- but these engines cannot handle anywhere near the boost we can. So I would try to keep C.R. below 9.6 if possible.

Willie

 

i agree with willie but i have run 58cc afr's with the standerd thickness gasket and up to 6 psi boost using water injection with no problems.that was with a stock 92 l98 cam and 1.6 roller rockers.your cam is bigger so i'd keep a eye on knock for your first wot runs.and i run 30 lb injecters with a custom prom.most likely swiching to a 7749 by spring.and i run a btm just for extra insurance and aid in tuning on the fly.

pete

 

what are you guys using for the pump for the water injection. I have the paxton sn2000 and the pump that they send in the kit is a joke. what kind of pressure do you need. I would thing that it would have to be higher pressure than the boost that you are running correct? but the real question is how much pressure do you need the be effective.

 

what are you guys using for the pump for the water injection. I have the paxton sn2000 and the pump that they send in the kit is a joke.

You mean the $9 plastic Anco windshield washer pump that Paxton labels as their "Detonation Suppression System"?? I use a pump from Carroll Supercharging.


What kind of pressure do you need?

Sufficient pressure to completely atomize the water/alcohol. The Carroll pump produces 100 pounds of pressure.

Willie

 

thank you.

 

i'm running a shure flo and it seems fine,way cheaper than the carroll kit and easly adapts into your existing system. puts out 60-70 psi. the factory kit is a joke under boost how much do you think ever came out?
pete

 

i've heard that using thicker head gaskets has a bad effect on the quench and can actually make you more detonation prone in that sense... i personally would just keep the compression where its at, and have the water injection come on at like 3 lbs of boost

 

where do you get the shurflo and how much is it?

 

i picked mine up at northern check them out at www.northerntool.com
make sure you get the high pressure model.
pete

 

we've been using kits from SMCenterprises.com to run denatured alcohol injection on our medium/big single 2jz applications. successfully run 36 psi on pump 93 gas with conservative EGTs and air/fuel ratio.

 

orderd mine tuesday from smc,looks like a better kit to me