Alright, I need some info confirmed and I also need to find out who is running extremely high CR and what octane and timing they are running.
First off, who is running compression OVER 11.6:1??
I am looking at running 11.8:1 and I need to know if anyone is doing this right now on pump gas SAFELY. If so, what octane are you using and what do you have your ignition timing set at (degrees)?? Also, did you have to make any other changes to avoid detonation/pinging??
Secondly, I am pretty sure that the answer to this question is yes, but I need to make sure. Please dont reply if your guessing or going by word of mouth. I need some good hard facts from experience… Will the b16b (CTR) pistons bolt up to the b18c1 (P72) rods without any machine work??
Jason,
u crazy guy… personal experience… hehe not yet. friend’s cars… yes. CTR’s on p72’s should mate up np. (99.9% sure on this one) u wouldn;t have them already to try? and as for high A$$ CR hows CTR pistons in a LSVTEC with a p72 head, on 91 oct sound? timing i believe was retarded by 2 degrees from stock ( i’ll call and find out for sure for u) added 15 psi to stock fuel pressure on stock 240cc injectors ( switching to 310s) Erick’s Racing modded p28 chip ( runs rich as hell too) oh… overheating is a BIG problem, upgrade to a fluidyne or PWR radiator (heh tryingtosee about getting a GB on the PWR’s), get a Mugen/Spoon Thermostat and thermo switch. also… try emailing Daniel ( battlecat) his crazy A$$ is running 12.4 on 93 i believe in TX/OK
Damn, if that ls/vtec is running standard bore pistons he is at 12.27:1 on 91 octane?? How the hell is he pulling that off?? Definately give him a call and see what he has to say and see what he backed the timing to. I am going to need to know since the highest octane we have available here is 92.
If I end up finding a P72 head then I will be at 12.09:1 CR and that is pushing it for a street car. That is why I am in the market for a PR3 head.
I dont want to get an engine together just to have to tear it apart shortly after getting it done due to unbearably high CR.
Do you have an email addy for Daniel?? Yeah, I am lazy…
I’m not going to add my .02 since I respect the “word of mouth” rule, but at these high cr’s, which we can all agree that you’re getting close to the brink of detonation, would it be best to have a few different sets of spark plugs with different heat ranges for warmer days or colder days? I would think the variance in temperature alone could cause a motor tuned during a cold day to detonate on a hot day. Has anyone done any work with this or have any background? I know it’s not answering your ? BR, but its on the subject I think.
Max - Your running 12.4:1 in your LS?? That is a LOT. What made you go that high, or did it just end up happening like that??
You suck for being able to get 94 octane… We are stuck with 92 down here. Oh well, at least it isnt as bad as california, hehe.
gen2ls/vtec - Yeah, that is on the same subject so its all good.
I have a friend up here running 11.6:1 in his civic hatch (EF) and it runs fine. Dan and I built his engine so I know for sure that is what he is running. Considering the fact that he has a substantially lighter car, I am not going to use his info as a solid reference.
Having a few different heat range spark plugs for flavor of the day wouldnt matter that much. Just go with what works best for the application and it will be alright.
Leo - Lookin’ good, but how would it run with stock injectors and no hondata tuning??
so a 20-40+ degree change in temperature wouldnt affect detonation? I know that the heat of the engine is going to heat the air in the combustion chamber to an appropriate temperature- maybe I’m thinking too hard on this :shrug: just wanted to bring up a different point of view
Originally posted by B R
[B]Max - Your running 12.4:1 in your LS?? That is a LOT. What made you go that high, or did it just end up happening like that??
You suck for being able to get 94 octane… We are stuck with 92 down here. Oh well, at least it isnt as bad as california, hehe.
gen2ls/vtec - Yeah, that is on the same subject so its all good.
I have a friend up here running 11.6:1 in his civic hatch (EF) and it runs fine. Dan and I built his engine so I know for sure that is what he is running. Considering the fact that he has a substantially lighter car, I am not going to use his info as a solid reference.
Having a few different heat range spark plugs for flavor of the day wouldnt matter that much. Just go with what works best for the application and it will be alright.
Leo - Lookin’ good, but how would it run with stock injectors and no hondata tuning??
Later,
BR [/B]
According to Dan that is what I’m running, although a lot of my friend’s over here say that’z impossiblee. Whilee I am not doubting Dan’s calculations, I will do some further research into this.
B16 pistons, 50thou off heead, 10 thou off the block.
Originally posted by B R
[B]
Leo - Lookin’ good, but how would it run with stock injectors and no hondata tuning??
Later,
BR [/B]
I’m sure I could’ve ran without the Hondata and still have avoided any detonation, but the injectors for sure would be necessary. Otherwise you could max out the duty cycle on the stock 240cc injectors and it still wouldn’t be enough to make a good A/F especially in the higher rpms. I would spend the extra money on the injectors and a S-AFC for the extra peace of mind.
Originally posted by E-DA9 According to Dan that is what I’m running, although a lot of my friend’s over here say that’z impossiblee. Whilee I am not doubting Dan’s calculations, I will do some further research into this.
B16 pistons, 50thou off heead, 10 thou off the block.
that sounds about right max. i used the compression ratio calculator and entered in the milling you did by changing the head gasket thickness (just subtracted 60 thousands) and it came up with 12.27:1, if you have oversized pistons that’d make it 12.35:1 I wouldn’t be surprised if dan’s calculations are more accurate though.
I am currently running 12.1:1 CR on 93 octane gas. Timing is set at 17 degrees, and it does not detonate with those settings. I am also using a stock P72 ECU, and 290cc obd2 prelude injectors, stock honda headgasket and head bolts. I would also agree that the 240’s are going to be way to small, and max out duty cycle. They just cant open fast enough to flow that much fuel through such a small hole.
The outside temps here are about 97+ in the summer, and that will also affect detonation. Cooler air is always better.
And 100% positive that CTR pistons will fit on P72 rods with no machine work, other than pressing them on.
Battlecat - Cool, that is some info that will come in handy down the road.
Considering the fact that I live in Seattle and we rarely, if ever, see temps above 95 on the hottest of days.
I have also noticed that you said that the 240cc injectors wont cut it, which I understand, but you mentioned that they cannot open fast enough to allow a sufficient amount of fuel in to compensate for the higher CR.
Since you are running a P72 ECU I know that you have peak & hold injectors and they open and close as necessary. I see how they wouldnt be able to open fast enough for your application, but what about non-obd saturated injectors?? Either way, the injectors will be upgraded sooner or later, but would saturated injectors do for a short while if the injectors dont get upgraded before the install??
My next questions is this… What injectors would be sufficient for this application?? Would 270cc be fine, or should I look at something more along the lines of 310cc. I am using those numbers because I plan on going with RC injectors at the moment.
How about a fuel pump?? Definate upgrade, or something that should be done in time??
If is should be upgraded, how many lpm should I be looking into??
I would really hate to build an engine and destroy it by leaning it out too much…
Thanks for getting a word in on this, Daniel. I appreciate it.
Well, a bigger injector wont have any issues with pulsewidth since it can actually flow more fuel per given opening. If you want to stay with saturated injectors, I believe the ob2 H22a injectors are that style, and rated at 330cc/min. Another issue with trying to run them so close to max duty cycle is they tend to get rather hot and malfunction.
If you are just going to be driving around town casually, you can most likely get along with the stockers, just back the timing up and colder plugs. I’d definately get some RC’s eventually, and 270 should be enough. If you want to go with like a 330, try to get ahold of a hondata, since sometimes they dont idle well with the factory honda fuel tables.
As for a fuel pump, probably as well. The main reason you need them is for the increased fuel pressure shortens the life of the pump, and actually decreases its output. Check around on hondata’s site, they have some of hte best info around town, and it’s all accurate. They have a lot of injector tech as well…
Right on, much more good information in that post.
I will go and read up on the hondata site and see what I can find out. I am pretty sure that I will be going with the RC 270cc injectors. I really dont think I will be needing anything more than that with an all motor setup.
I will have to figure out what capacity fuel pump will be needed for this application. Hopefully I can find that out on the hondata site, or at least find a good link to what would be optimal.
I havent done any research on fuel pumps to date, so that would be a good thing for me to educate myself on at the moment…
Thanks again for all the help and I will let you know if I come across anything else I might need some guidance on.
very helpful topics guys, question: what type of aftermarket fuel pump is available for a 91? i have searched high and low for one that will fit-nothing.what are you guys with 91’s using? i am also running a high C/R ls/vtec. around 12:1, gsr injectors, FPR@ 45 psi, skunk2 PR3 ecu. i believe the weak link here is the pump first, then injectors. any ideas??
Originally posted by lowntegra
[B]very helpful topics guys, question: what type of aftermarket fuel pump is available for a 91? i have searched high and low for one that will fit-nothing.what are you guys with 91’s using? i am also running a high C/R ls/vtec. around 12:1, gsr injectors, FPR@ 45 psi, skunk2 PR3 ecu. i believe the weak link here is the pump first, then injectors. any ideas??
bryan [/B]
You would probably get a lot more help out of your questions by starting a new thread rather than posting at the bottom of a already long one.
You might want to look into companies such as Walbro for the fuel pump, or just do a search for them and see what you can find out.
