I am considering purchasing a procharger for my 350ZR. I was told that at
11psi, the crank horsepower is increased to approximately 500. The procharger is a completely self contained unit with its own oil reservoir. I have heard recently that some Z's have blown the engine with this procharger because it increases the compression ratio significantly above the stock 10.3 to 1. Anyone have any experience with one of these units on their Z?11 PSI of boost on a 10.3 to 1 comp engine on pump gas is a recipe for a dead engine. There is no way you would be able to keep detonation at bay. It would be cool if you could run say 8.0 to 1 with that much boost (or 10.3 to 1 and that boost with 118 octane leaded race gas) but with a stock comp engine and unleaded pump gas, you're asking for broken pistons.
BTW you might want to ask what a rebuild costs. If these are anything like the earlier Z's as far as complexity, figure about 4-5K.
What if you increased the fuel pump size, used larger injectors and retarded the timing with an ECU reflash. Would 9 PSI be safe on the VQ35DE?
I took a look at this kit. IMO this kit has all the right ingredients except one. The 350Z has a compression ratio of 10.3 to 1. This compression is not boost friendly. The 300ZX n/a has a compression ratio of 10.5 but the "big brother" twin turbo compression is 8.5 to 1. The 1990-1996 300ZX TT also has larger oil jets to cool the bottom of the pistons than the normally aspirated model. The super charger kit should have included a thick metal head gasket to lower the compression ratio of the 350Z. To do this modification right the pistons should be replace to lower the compression to about 8 to 1 maximum and have a method of cooling the pistons. Also while your at it install an oil cooler.
-LJ
Ahh, I was curious about the possibility of lowering the compression for a Greddy TT install.
Reiver
I read about the Greddy TT install and that system is a better bet for two reasons.
IMO If you are going to do a head gasket you might as well swap the pistons out, you will have half the engine apart anyway.
Not on pump gas and if you retard the timing enough to keep things in one piece, it's going to end up being a dog. BTW you can't just increase the injector size without changing the whole fuel map to go with it. To boost one of these engines, the compression needs to be lowered.
I thought you just meant lowering the timing, sorry I missed what you were saying. Are -you- capable of remapping the fuel curve? "Reflashing" the ECU sounds simple but it's not and doesn't mean it's remapped for different injectors unless someone changes that specifically...
Go ahead and do all this and let us know what happens! :-) BTW I'd price a rebuild to make sure you can afford to blow this engine up... My guess is it's about a 4-5K rebuild after you blow the ring lands off a piston.
You asked for advice and I gave it. Name -one- boosted engine that runs
10.3-1 comp from the factory. There is a reason they lower the comp on boosted engines. Ignore this and learn the hard way why they do it that way? Sounds like some people already have!
And with the right pistons you will retain some squish which should help with detonation and power, also a thick gasket will screw up the cam timing unless the sprockets are adjusted. A thick head gasket is a compromise at best.
Get back to us in 50K miles. Boosting a 10.3 to 1 engine using stock internals is a hack way of doing it and isn't going to be reliable.
I read where you linked, didn't have much info other than a phone number.. I sure can't stop anyone from doing this and actually I hope lots of people around atlanta do this in the way you sugest. Blown engines make us LOTS of money!! I've made loads off of those electronic boost controllers on the twin turbo 300z's :-)
You obviously didn't look at the site for our shop, just finishing an intercooled turbo 77 280 Z project for a customer... Done lots of twin turbo hotrods doing internal engine mods (cooling mods and head work) using sport turbos and big intercoolers etc. If anyone wanted me to do this FI mod to a 350Z, I'd HIGHLY recomend them lowering the compression first and if they didn't want to, I sure wouldn't stand behind whatever happened.
Whatever... They aren't going to be reliable at nearly 10PSI with 10.3 comp as witnessed by your 'claimed' 5% engine failure rate this quickly in the car's life. 5 to 6 PSI might live but 9-10 isn't going to. In the summer climate in Atlanta they sure wouldn't last very long if they were run very hard. Blowing a shitload of fuel and backing the timing down -IS- a hack and will cause other problems such as high cyl wall wear, exh valve heating, exh manifold cracking, oil contamination, ruined cats etc. These are the reasons the OEM's don't use high compression on boosted engines. Why do you think they lower the compression when it adds to the lag a turbo/boosted engine has?
You sound just like the people who say NOS is OK on a stock comp engine until they roast it.. Like I said to the OP, I would seriously consider what a rebuild costs before I tried this stuff. If you can't afford to replace the pistons when the kit is installed, will you be able to afford a major overhaul after you break some pistons later and maybe trash other stuff in the process?
Cute.
Just remember not to cry when your engine is hosed. :-)
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