8.3:1 or 9.0:1

[DSMinn0vati0ns]

hey everyone i was looking for some advice or a gain of knowledge in building a motor... i wanna know what the difference would be if i went to 9.0:1 and what parts i would have to change to compensate for the different piston size... also i was thinking about boring it out, and to what bore is a good combination with the size of the pistions... if anyone could help me out so i can learn that would be great.. thanks a lot everyone!

 

[LT1andDSM]

8.3.1 More boost bigger tuning window
9.0.1 Less boosT smaller tuning window (for a beginner)

 

[Injected]

Split the difference and shoot for 8.8:1.

I wouldn't go as high as 9:1 if I didn't have at least 93 octane at the pump and a great (not just good) fuel management system like DSMLink.

 

[sleek98]

i would just stick with 8.5 or 8.3 anything higher will make it harder to tune unless high octane gas used. Some will say its the same to tune but i have found it more difficult.

Chris

 

[jo1]

it only a margin of error.... for me lower compression give me higher margin of error.

 

[Injected]

it only a margin of error.... for me lower compression give me higher margin of error.

Not true... The 7.8:1 of the stock 1G feels much more sluggish off boost than the 8.8:1 of the Evo 8 & 9. For a street driven car, I say 8.5 to 8.8 for boost applications of up to a little over 20 psi.

 

[DSMinn0vati0ns]

say if i did go with the 9.1... what else would i have to do for them to fit in the motor? or are they basic drop in's?


also is it worth it to bore out the cylinders? pro's? con's?


way to many choices... help me narrow it down

 

[sleek98]

The pistion dome is the difference in compression ratio. They will fit your rods as long as you get a matching set, 6 bolt pistions with 6 bolt rods, or 7 bolt rods and 7 bolt pistions.

Also I wouldnt recommend boring the bock unless there is damage to the cylinder, or it is too far out of spec for it to get a hone job. Too many mistakes can be made in boring it and you will end up with an expensive paper weight when the pistions slap from the wrong clearences.

 

[DSMinn0vati0ns]

this is very true. so which would be the better set up for power? in your opinion...

8.5 wiesco, golden rods or 9.1 wiesco, golden rods...

currently right now with stock internals i made 310 @ 16lbs of boost... and i see that your car made the same hp as me... how much boost were u running? sorry for getting of topic for a second.

 

[jo1]

Not true... The 7.8:1 of the stock 1G feels much more sluggish off boost than the 8.8:1 of the Evo 8 & 9. For a street driven car, I say 8.5 to 8.8 for boost applications of up to a little over 20 psi.

I'm talking about margin of error during tunning.....

 

[sleek98]

this is very true. so which would be the better set up for power? in your opinion...

8.5 wiesco, golden rods or 9.1 wiesco, golden rods...

currently right now with stock internals i made 310 @ 16lbs of boost... and i see that your car made the same hp as me... how much boost were u running? sorry for getting of topic for a second.

15 psi, with a 8:1 afr and 14* of timing. im going to get it redynod with the bigger cams, 25 psi and tuning sometime in the next couple of weeks hopeully i can hit 400 whp.

this was on a pte3134 and a 8.5 c/r my numbers are also on a mustang dyno.

chris

 

[blackGSX2g]

I don't find that its really all that difficult to tune out. I am running my 50 trim at 30psi daily on pump gas with 9:1 compression.

 

[dsm dork]

I don't find that its really all that difficult to tune out. I am running my 50 trim at 30psi daily on pump gas with 9:1 compression.

What timing are you running, a/f ratio and tuning system?

 

[Injected]

What timing are you running, a/f ratio and tuning system?

No kidding. Mas info por favor.

 

[blackGSX2g]

Peak timing is around 18-20* at 7500 rpm tuned quite rich with DSMLink v2, a zeroed out GM MAF, and a relatively unmodified timing curve. I'm adding a few degrees down low, but about 5500rpm and up hasn't been touched. I don't have a wideband yet so AFRs would just be a useless estimation. An LC-1 wideband is next on my list.

 

[dsm dork]

Mind posting some logs?

30psi on 93 only with a 50trim is quite quite impressive.

 

[blackGSX2g]

Absolutely. I haven't logged my car in forever, but I'll go fire up my DSMLink laptop this weekend and get some on this computer. It would be good to get some feedback on my logs, tuning is definately not my strong suit.

 

[nightspeed87]

Peak timing is around 18-20* at 7500 rpm tuned quite rich with DSMLink v2, a zeroed out GM MAF, and a relatively unmodified timing curve. I'm adding a few degrees down low, but about 5500rpm and up hasn't been touched. I don't have a wideband yet so AFRs would just be a useless estimation. An LC-1 wideband is next on my list.

Wow, 30 psi, 9:1 comp, 20 deg ign advance... You must be on race gas or water inj right'?

 

[andymoraitis]

Wow, 30 psi, 9:1 comp, 20 deg ign advance... You must be on race gas or water inj right'?

Nope. Matt runs straight E85 and he still has more tuning to do. Methinks I'll take a trip up to Kalamazoo this winter and spend some time on Link with him.

I run 8.8:1 with the intake cam advanced 5 degrees and 25 psi on straight 93 with a zero knock tune on a 2.3 stroker at 8 degrees of timing advance. Once I add methanol (I run a Dejon Sidemount) I'll bump the timing to 18. On 100 octane I can run the same 8 degree tune at 30+ psi but the clutch won't hold it. Keep in mind that where Matt's motor sees around 170 compression with his cams on the 2.0, my cam advance nets me 190 across and therefore necessitates less timing. He also ran a rich A/F on 93 and on the E85 as well while mine is at 11.5:1

I agree that tuning a higher compression ratio will require less timing, but having more compression off boost makes the motor more responsive and fun to drive. Having some extra grunt surely is a good thing.

 

[blackGSX2g]

Nope. Matt runs straight E85 and he still has more tuning to do. Methinks I'll take a trip up to Kalamazoo this winter and spend some time on Link with him.

Actually I've ran 30psi on both 93 octane as well as E85 with no problems. I can say that tuning WOT is way easier with E85, but it can be done with both with just the fuel mods in my profile. I was planning on running meth injection, but I haven't had any problems controlling knock so I'll hold off.

I'm waiting for my serial to USB adaptor so I can hook up DSMLink again, my old laptop didn't like sitting out in the garage un-used for months and crapped out.

 

[bryanwheat]

I got a quick question for you guys running e-85. I sometimes run like 50 percent e-85, and 50 percent 93 octane. I usually have to richen it up 3 to 5 percent, being that the ethanol burns faster than gasoline. Now i have been wanting to just switch to e-85 full time. Can you give me a rough estimate on the difference in tuning, as far as percentages that you use when switching from 93 to e-85? Also do you know if walbro pumps are compatible with ethanol?, and Also the fuel injectors, and fuel hoses, do you run steel braided? Hit me up. I want to switch tomorrow, and get started on tuning. LEt me know. Thanks

 

[wishihadatalon]

E85 burns slower

 

[oztofrdm]

I got a quick question for you guys running e-85. I sometimes run like 50 percent e-85, and 50 percent 93 octane. I usually have to richen it up 3 to 5 percent, being that the ethanol burns faster than gasoline. Now i have been wanting to just switch to e-85 full time. Can you give me a rough estimate on the difference in tuning, as far as percentages that you use when switching from 93 to e-85? Also do you know if walbro pumps are compatible with ethanol?, and Also the fuel injectors, and fuel hoses, do you run steel braided? Hit me up. I want to switch tomorrow, and get started on tuning. LEt me know. Thanks

Dont even bother on a street car, just to run e-85 you would need: 10an feed line, a1000 fuel pump, 2 10an fuel filters, 8 large injectors, aem or better. that and metonal burns almost twice as fast as normal gas so you will be filling up quite a bit.

A normal injection kit from coolingmist is more than enough for a street car. In my car and a friend with an auto both run there biggest injector on 35r's. I never got back to the track since i put it on but he went 11.0 with 30psi and a 50shot all on a full weight street trim auto, no cams or smim, my car (spd.) i was getting NO knock on boost up to 35psi untill my stock block ripped the wrist pin off the piston

 

[oztofrdm]

E85 burns slower

poor a bit of methonal on your hand and then regular gas and tell me which one evaporates quicker

 

[wishihadatalon]

poor a bit of methonal on your hand and then regular gas and tell me which one evaporates quicker

Read up on it. Yes you need ~30% more fuel for the same action but do you wonder why you can get away with more timing with e85. It burns at a slower rate

In a combustion engine it's a different story. Gasoline is vary inefficient in a combustion engine. Most of it's energy is wasted as heat. Ethanol burns slower more efficient so more of it's energy can be transferred to due work.
quoted: http://www.news-leader.com/apps/pbcs.dll/article?AID=/20061114/OPINIONS03/611140311/-1/BLOGS06

The second is engine design. Ethanol has a high octane (100+), so it burns slower than gasoline or gasohol (10% ethanol). Flex-fuel vehicles compensate for this, using the electronic engine control module to alter such things as ignition timing.
quoted: http://farmindustrynews.com/mag/farming_talk_20/

Octane is a strange rating system, as they don't really count the number of octal hydrocarbons as they do when they name methane (4), propane (3), or butane, (C4H10). Octane would be, naturally, 8. But rather than measuring a percentage of octal hydrocarbons, octane is an index of how slowly a fuel burns. The slower, the better, so that the explosion of the fuel/oxygen mixture can push the piston down rather than slam it down.
quoted: http://running_on_alcohol.tripod.com/id28.html

e85 has a much higher octane rating than 93. I believe it is somewhere around 105 ish.

Just found another good article
http://wildcat.arizona.edu/home/ind...story_id=715bbc83-9341-43a8-9a48-96bb9690ace7