If I raised my compression to approximatley 10.7-1 could I get away with a stock tune? Hp is in the furture but for now what do you think?
Let me guess? 086 head? If so, the compression with stock pistons is 11.4:1 or 11.7:1 depending on the year of the engine. Not 10.7:1.
You could get away with that compression but you need 91-93 octane MINIMUM.
Gilles
2.3 Ho
Well Im thinkin 10.7-1 after certain mods. But thanks I think they sell 92 around here but I wanted to make sure before I did the work. I guess I could always add octane booster too if I needed.
octane booster is @!#$, don't waste your time with it
Ok as long as i can run 10.7-1 and get away with 92 octane with a stock tune until late summer(hp tuners) all will be good.
you'll be fine with 92 octane and 10.7:1 on the stock tune.
Gilles
2.3 Ho
In case you were wondering, I have been running straight low octane and haven't recieved any DTC's regarding knock (just one related to EVAP)
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"Youth in Asia"...I don't see anything wrong with that.
Thanks, whats your final compression ratio about 10.7 with the 9-1 pistons? My 086 is on the way
it needs a rebuild but thats ok. Im lookin to have it on by early summer along with some other mods. Did you notice a pretty large gain with the head? Lookin at your mods by next tax return time(for the bottom end) I'll have a similar setup but im using HO cams. Do you have an Idea what you'd run in the quarter?
Haha I just saw the 10.7-1 in your mods I looked right over it the first time i looked...I knew I saw 10.7-1 with the 9-1 pistons somewhere.
Syntar wrote:Did you notice a pretty large gain with the head?
Did everything all at once (oil pump, head, pistons, exhaust, throttle body), so I couldn't tell you
Syntar wrote:Do you have an Idea what you'd run in the quarter?
Nope...But I can tell you that it flies from about 3500 to when it shifts at 6500
Syntar wrote:I'll have a similar setup but im using HO cams.
Mine are in the mail
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"Youth in Asia"...I don't see anything wrong with that.
Not to thread jack... but with the 086 head what pistons do you need to get a cr of 12 or so? im looking to build a n/a ld9. Thanks.
No problem...If you stay with the stock ld9 pistons and the 086 head you will have 11.5-11.7 cr depending on the year of your engine. But you need to be careful of which cam setup you use due to clearance issues. I read that the secret cams clear but not the HO cams(which I am gooing to run).
hmmm..... I later want to run Ho cams or w41 cams. I have the screct ones right now.... would I need custom pistons to run the HO or w41 cams? Thanks.
I was told that if I wanted to run high compression then yes custom is the only way to go. If 10.7 compression is acceptable then get the stocker 9-1s and your HOs or W41s are supposed to fit, although I have not personally tried it yet.
11.5-11.7 is with stock pistons and the head. What would boost me too 12? A thicker/thinner gasket? Or is that cr with stock pistons fine for n/a? I want the best power out if it. Im going to be shooting a 75-100 shot in about a year... as well as upgrading to HO or w41 cams. Thanks.
If I were in your shoes and planing on shoothing 75-100 shot I would opt for the custom forged pistons. I hear nitrous and factory cast pistons dont like each other all too well. Like I said above HOs or W41s wont clear a stock piston anyway so if you get the custom ones then you can pick your compression ratio and still clear the valves.
I meant stock forged pistons.
That would work fine for the nitous but it still woldnt clear the cams.
A thinner head gasket would raise static compression. If you want .410" lift cams to clear and 12:1 compression, you will need pistons similar in shape as Gilles's, where the piston raises in the center and reliefs are cut back to decrease the compression. Because the ld9 has a longer stroke/larger displacement than the LGO, the center of the piston doesn't have to be raised as radically to achieve the same static compression ratio (granted, his were also cut to clear .430" cams). Just talk to Karo and tell him what you are doing...He will get you the pistons you need.
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"Youth in Asia"...I don't see anything wrong with that.
Yes the stroke/bore is different on the 2.4 but the heaad also has a bigger combustion chamber witch could result in a dome close to mine.
Gilles
2.3 Ho
Listen to Brian...he's the man! He knows his stuff cause hes actually done it.
Mfk-223 wrote:Yes the stroke/bore is different on the 2.4 but the heaad also has a bigger combustion chamber witch could result in a dome close to mine.
On the stock head sure, but...
Daniel Noriega wrote:11.5-11.7 is with stock pistons and the head. What would boost me too 12? A thicker/thinner gasket? Or is that cr with stock pistons fine for n/a? I want the best power out if it. Im going to be shooting a 75-100 shot in about a year... as well as upgrading to HO or w41 cams. Thanks.
I'm pretty sure he is talking about "the head" as the 086 head.
A flat top piston on a quad 4 won't result in 11.7:1 CR, so there isn't as much volume needed to be taken up in the combustion chamber of a hybrid to make up the extra .3, but it does have to be raised enough so that when reliefs are cut, there is 54.36 cc's in the combustion chamber. A quad 4 only needs 51.37 cc's in the combustion chamber to achieve 12:1 static compression.
Edited 1 time(s). Last edited Thursday, March 15, 2007 10:20 AM
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"Youth in Asia"...I don't see anything wrong with that.
Yeah I forgot that he's going with the 086 head.
FYI, my pistons have a 3.12CC dome.
Gilles
2.3 Ho
