ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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 Posted: Tue Nov 05, 2013 12:52 am Post subject: |
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To directly answer your question:
All that said, I do NOT think that a water-meth injection kit is the best bang for the buck on a normally aspirated car. It's highly subjective and arguable what benefit, if any, you would realize.
There are many other things you should consider investing in first, not the least of which is increasing compression ratio, which can be done with minimal additional mods and expense by installing a thinner Cometic MLS gasket. On an otherwise stock US-spec early NA, the .027" gasket will only increase CR from 8:1 to 8.3:1, whereas on the later model US cars, it will increase from 9:1 to 9.4:1, which is a bit better than the stock Euro-spec 9.3:1. You can play with the numbers yourself right here.
The next best bang-for-the-buck would be installing 931 pistons in the short block. With no other mods, US-spec S1 931 pistons will bring you up to 9.7:1, and US-spec S2 931 slugs will yield 10.6:1.
The problem with all of this is that you have the early 1977 head with much smaller valves and much poorer flow. So anything that you do without addressing the primary weak point in your particular build is going to be rate-limited by the head. So the best advice is to address the shortcomings of the head FIRST, and then do power adders after.
Unless you are a skilled machinist with experience and specialized tools required for the 924 head (try finding the correct bit for boring out the valve guides, for example), head work is likely to cost you at least $2K, and that doesn't include cam or lightweight lifters. But if you're really looking to get the most out of your motor, my advice to you is to start with the head. Install a Big Valve Kit, the Sten Parner solid (lightweight) lifters, and a Stage 1 Integral Cam. Have your machinist port the head and intake. THEN dive into the rest of the power adders (like increased CR, bigger throttle body, free flow header, crank scraper, and maybe last of all water-meth).
Sorry to say, but on your 95BHP 77 motor (with its literally retarded head), you are unlikely to see much if any benefit from the water-meth kit. I strongly suggest that you read and re-read the Performance Mods thread (which Stefan pointed you to in one of your other threads), and in particular the section on Heads.
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erstwhile owner of just about every 924 variant ever made |
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924 FAQ (Technical)
