h4nsm0l3m4n Posted March 20, 2010 Share Posted March 20, 2010 I've been studying to build a higher compression L28 for my autocross car. Seems like most FP Z cars use E31 heads but those are getting hard to find. I'd like to use a more common N42/N47 or ,ideally, a P90/P79 head. However since the P heads are out of the s130 I dont think you can use them on the s30 cars.. I checked the rulebook and all it says in the rulebook in regard to cylinder heads is: 1. The original or a specified alternate cylinder head shall be used. Any valve guides and valve seats may be used. 2. Compression ratio may be altered by machining, using any head gasket(s), or elimination of head gasket(s). Could I use a P90 or P79 head in a FP autocross car? Quote Link to comment Share on other sites More sharing options...
johnc Posted March 21, 2010 Share Posted March 21, 2010 I've been studying to build a higher compression L28 for my autocross car. Seems like most FP Z cars use E31 heads but those are getting hard to find. I'd like to use a more common N42/N47 or ,ideally, a P90/P79 head. However since the P heads are out of the s130 I dont think you can use them on the s30 cars.. I checked the rulebook and all it says in the rulebook in regard to cylinder heads is: 1. The original or a specified alternate cylinder head shall be used. Any valve guides and valve seats may be used. 2. Compression ratio may be altered by machining, using any head gasket(s), or elimination of head gasket(s). Could I use a P90 or P79 head in a FP autocross car? Not in a 240Z. E31 or E88 for the 2.4L engine. A later, bigger valve E88 is a good choice. Quote Link to comment Share on other sites More sharing options...
DAW Posted March 24, 2010 Share Posted March 24, 2010 Not in a 240Z. E31 or E88 for the 2.4L engine. A later, bigger valve E88 is a good choice. I have an E31 with a fresh valve job and the larger L28 exhaust valves installed. Very reasonably priced in Seattle. DAW Quote Link to comment Share on other sites More sharing options...
Mack Posted March 25, 2010 Share Posted March 25, 2010 (edited) Find yourself a maxima N47 head and fit it with 280Z N47 intakes if you want. TONS of compression (itty bitty 39cc combustion chamber) and really nice quench. EDIT: post number 666, awesome. Edited March 25, 2010 by Mack Quote Link to comment Share on other sites More sharing options...
hoov100 Posted March 25, 2010 Share Posted March 25, 2010 Honestly, if you machine off the numbers of the cylinder head, they will never be able to tell the difference, unless they put it next to a stock one. Do any of the scca techs have a source of info for the z motors? or is it based on there call? Quote Link to comment Share on other sites More sharing options...
skib Posted March 25, 2010 Share Posted March 25, 2010 Ill be using an E31, I might be able to source you one if your interested Quote Link to comment Share on other sites More sharing options...
johnc Posted March 25, 2010 Share Posted March 25, 2010 Honestly, if you machine off the numbers of the cylinder head, they will never be able to tell the difference, unless they put it next to a stock one. Do any of the scca techs have a source of info for the z motors? or is it based on there call? The 240Z has been raced with SCCA since 1970. Do you really think something as bush-league as that wouldn't be spotted by SCCA Techs and/or your competitors? FYI... I'm a SCCA Tech. Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted March 25, 2010 Share Posted March 25, 2010 Quote Link to comment Share on other sites More sharing options...
johnc Posted March 25, 2010 Share Posted March 25, 2010 Nobody f***s with the Jesus! Quote Link to comment Share on other sites More sharing options...
Two80z4me Posted March 25, 2010 Share Posted March 25, 2010 I have a 78 280z with a Zx p79 head motor in it and even z car techs have put me in the stock class... Quote Link to comment Share on other sites More sharing options...
hoov100 Posted March 25, 2010 Share Posted March 25, 2010 The 240Z has been raced with SCCA since 1970. Do you really think something as bush-league as that wouldn't be spotted by SCCA Techs and/or your competitors? FYI... I'm a SCCA Tech. they have been racing circle track for over 50 years and we manage to get away with stuff like that. Quote Link to comment Share on other sites More sharing options...
woldson Posted March 26, 2010 Share Posted March 26, 2010 If you get away with something, is it then ok? Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted March 26, 2010 Author Share Posted March 26, 2010 (edited) If you get away with something, is it then ok? That's sort of the principle I'm going by. Most tech people here probably wouldn't realize or care that the p79, etc, heads came out of a later car. I don't plan on competing on a national level either, where inspectors might be more interested in whats inside the car. Heck, most of the time I don't even specify a particular class when I run, so really I can do pretty much whatever I want... I'm trying to build the car per SCCA rules mostly because I thought it would be fun and more interesting to build the car to a particular ruleset. Edited March 26, 2010 by h4nsm0l3m4n Quote Link to comment Share on other sites More sharing options...
hoov100 Posted March 27, 2010 Share Posted March 27, 2010 If you get away with something, is it then ok? More along the lines of it's "if not in the rule book its not a rule" there is no interpretation of the rule book, there is what is written and what is not. Quote Link to comment Share on other sites More sharing options...
woldson Posted March 27, 2010 Share Posted March 27, 2010 More along the lines of it's "if not in the rule book its not a rule" there is no interpretation of the rule book, there is what is written and what is not. So that is why their are warnings that are nuts, like cruise control on RV's. And others. I do see your point, however, dealing with contract of absurd sizes is also a product of this. I do understand being unique about rules as needed, remember mercedies and their push rod engine years back, now that was ingenius and well within the rules. Oh and BTW Hoov, I do like you, I find your comments clever and well thought out, so my comments are ment to shine some light, not castigate. Quote Link to comment Share on other sites More sharing options...
MAG58 Posted March 27, 2010 Share Posted March 27, 2010 Nobody f***s with the Jesus! Quoted. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 29, 2010 Share Posted March 29, 2010 More along the lines of it's "if not in the rule book its not a rule" there is no interpretation of the rule book, there is what is written and what is not. Except for the catch all rule the SCCA has in the GCR and the Solo2 rule book: "If a modification is not specifically authorized in this or previous applicable sections of these Rules, it is not allowed" Basically, if it doesn't say specifically you can, you can't. Quote Link to comment Share on other sites More sharing options...
Two80z4me Posted March 30, 2010 Share Posted March 30, 2010 dang, the techs in MT are slacking, some tried to tell me 78 280z's came with a turbo option :/ I guess I can getaway with turbo's here until I go to nationals lol Quote Link to comment Share on other sites More sharing options...
burninator Posted April 1, 2010 Share Posted April 1, 2010 The rules state: G. Cylinder Head1. The original or a specified alternate cylinder head shall be used. Any valve guides and valve seats may be used. 2. Compression ratio may be altered by machining, using any head gasket(s), or elimination of head gasket(s). I'm not sure how I'd take that rule... you could take that to mean that only the original cylinder head that came on the engine may be used, but since 240s and 280s are listed on the same line in the appendix their engines can be swapped. Does the fact that any engine from the 3 models can be used that their heads can be swapped between them as well? I wonder if it's been protested before. If others are doing it without being protested you could probly get away with it, but you can write the PAC/SEB for clarification: seb@scca.com Anyways, by whatever interpretation of that rule you pick the p-heads are not allowed. dang, the techs in MT are slacking, some tried to tell me 78 280z's came with a turbo option :/ I guess I can getaway with turbo's here until I go to nationals lol That's only because I've never inspected your car. I'll have to school our techs. Quote Link to comment Share on other sites More sharing options...
johnc Posted April 1, 2010 Share Posted April 1, 2010 I was mistaken. You can put a P series head on a 2.4L engine although it doesn't make sense given that the minimum weight in FP is 1,900 lbs. With the weight/displacement formula a 2.4L could weigh 1,800 lbs. but can't. probably better to build a 2.8L which has a 2,100 lb. minimum. Quote Link to comment Share on other sites More sharing options...
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