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Thats why its a big thing on older muscle cars (changing cast iron heads to alum.), so its eaiser to run higher compression, and or coruse make the car lighter.

2nd opinion.

7th paragraph down (http://www.yearone.com/Articles/article_dp.asp?AID=7)

Cylinder head material also affects the overall package. Typically, older engines originally used cast-iron cylinder heads, while in the vast majority of modern designs aluminum alloy is the material of choice. Aluminum heads are considerably lighter than cast-iron versions, but more than weight is affected by material type. All things being equal, cast-iron heads usually make a bit more power than aluminum heads simply because cast iron is a better thermal insulator. The iron does not transfer heat as well, which means more heat is retained in the cylinder and contributes to the combustion process. Things are rarely equal, though. Since aluminum transfers heat more effectively than iron, engines with aluminum heads can run a higher compression ratio than iron-headed engines. Higher compression ratios translate to more power, but the higher the compression ratio, the higher the chances of detonation, which is a premature and uncontrolled exploding of the air/fuel mixture in the cylinder. Detonation is dangerous and if it occurs continuously, major component damage will result. Excessive heat and isolated hot spots within the combustion chamber are primary causes of detonation, and aluminum is less susceptible to these causes than iron.


Matt
 

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mRek9R said:
Thanks buddy! I used 88-89 Integra ZC pistons(p29/pm7). As far as pump gas, if i keep the compression ratio at 12:7:1, just using pump gas will cause too much pinging and detonation. I'd have to retard SO much that it would just become unreliable and weak. Right now i'm trying to get a thicker headgasket to lower the compression ratio down to at least 11.5:1 where it'll be more manageable until i get myself aquainted with a p28 and uberdata. A z6 head would lower the compression, but the y8 actually raises it ALOT...so i do have a spare z6 head here the might have a bullfrog cam, so i'll get back to you guys on what happens! 8)
You can tune ignition timing with premium pump gas without all that toluene and still make nice power safely. Builthatch over at d-series.org was doing it with a 13:1 Y7.

A Z6 head has the same chamber as a Y7, there won't be any change in compression between those to heads. The Y8 is smaller by only 1.8cc, which equals about .4 higher c/r compared to a Z6. The overbore also increases about .1 c/r. If the pistons were 12:1 with stock bore in a Z6, then your setup will yeild around 12.5 c/r
 

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Discussion Starter #24
klungemonger said:
You can tune ignition timing with premium pump gas without all that toluene and still make nice power safely. Builthatch over at d-series.org was doing it with a 13:1 Y7.

A Z6 head has the same chamber as a Y7, there won't be any change in compression between those to heads. The Y8 is smaller by only 1.8cc, which equals about .4 higher c/r compared to a Z6. The overbore also increases about .1 c/r. If the pistons were 12:1 with stock bore in a Z6, then your setup will yeild around 12.5 c/r
thanks klungemonger, i'll talk to him..8)
 

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klungemonger said:
Definitely anxious to learn of your results, I'm hoping to have the A1 pistons with mini-me done this summer also. I'll have a shop dyno tune it with Hondata S200 though, I don't want to fool around with Uberdata.
Do you have any #s on your hatch, be it HP or 1/4 mile times. I was checking out your sig. And was wondering what those mods would do to my HB. BTW what kind of LSD is that.

Thanks, Matt
 

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i like this project and i do wanna see numbers, soooo plz send em to me when u get em, laters-
 

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terboracer said:
so you got new pistons and headbolts, and a y8 head? what else is different to make it high compression?
Head with smaller chambers + different pistons are the only items required to raise compression. Just one of them will raise c/r, together they just raise it more. A slight overbore with stock pistons will raise it a little also, but any mods outside the cylinder & combustion chamber has no effect on compression.
 

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J.O.A.T said:
Do you have any #s on your hatch, be it HP or 1/4 mile times. I was checking out your sig. And was wondering what those mods would do to my HB. BTW what kind of LSD is that.
No numbers to post as yet. I'm very pleased with the mods so far, my car is much more fun to drive. The Y8 tranny made a huge difference, of course. The lsd is a Phantom Grip, however if given the option again I would buy the OBX diff which is an imitation Quaife. A good deal for half the price of the Quaife. I paid $180 for my lsd and installed it myself since it just goes inside the stock diff. Replacing the whole diff requires measuring/shimming which I can't do. Normally though the PG is like $260, so it's worth it to get the real lsd for another $140.
 

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Cool. Thanks. What did you get your y8 tranny for? And where were you looking?

Thanks,
Matt
 

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I found it online but by coincidence it was a guy only about an hour from me so no shipping. I picked it up for like $170 or so. Keep you eyes on Ebay, only watch out not to get raped on shipping. I've shipped trannies through FedEx ground to business addresses for between $30-$50. Some idiots try to get over $100 for shipping.
 

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Thanks.

Matt
 

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I either want to use the y8 or d15 trans if I can find one with an lsd. Im having a hard time finding y8 trannys. Im going to need one soon, 3rd gear is really starting to go.

Matt
 

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Discussion Starter #36
J.O.A.T said:
I either want to use the y8 or d15 trans if I can find one with an lsd. Im having a hard time finding y8 trannys. Im going to need one soon, 3rd gear is really starting to go.

Matt

ya, y8s are a bit harder to find. The junk yard here wants $600 for it..i was like ***K NO!! 8)
 

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Try calling Nagano Japanese (www.naganojapanese.com) they used to be a SHO sponsor and I remember them saying you could pick up the D15B lsd tranny for around $450 I think with shipping. I could be off but I seem to remember that. Great deal, just getting an lsd like that would normally cost that much. I'll try to search archives and see if I got that right.
 

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Discussion Starter #38
klungemonger said:
Try calling Nagano Japanese (www.naganojapanese.com) they used to be a SHO sponsor and I remember them saying you could pick up the D15B lsd tranny for around $450 I think with shipping. I could be off but I seem to remember that. Great deal, just getting an lsd like that would normally cost that much. I'll try to search archives and see if I got that right.
damn, i'd love to add a JDM LSD Dseries tranny...maybe i'll buy the OBX LSD and try it out...8)
 

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klungemonger said:
Try calling Nagano Japanese (www.naganojapanese.com) they used to be a SHO sponsor and I remember them saying you could pick up the D15B lsd tranny for around $450 I think with shipping. I could be off but I seem to remember that. Great deal, just getting an lsd like that would normally cost that much. I'll try to search archives and see if I got that right.
Thanks. Id be willing to pay that. Im going to give them a call tomarrow. Can anyone thorw up the different ratio #s for the y7,y8, and d15 trannys. Rep for who ever does it.

Thanks,
Matt
 
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