10.5 compression on 7lbs of boost

[kyosoeg6]

has anybody here had good results or did it require alot of tuning.any info would help.i prefer less boost more compression over more boost less compression

[Diablo]

It can be done, but fuel management is the key, I'm lookin to do the same in the near future.

[kyosoeg6]

ya i have a aem fuel rail aem fuel reg vortech fmu rc 310s and a vafc.i hope this will be enough to get tuned.ill keep u posted

[kommon_sense]

you don't need the fuel rail. The stock rail will flow more than enough fuel. Also, ditch the vortech. You won't need it with the VAFC. However I don't know if the 310s will get the job done. I would also throw an adjustable fpr into the picture.

[SilentWrath*]

I would also throw an adjustable fpr into the picture.

he does

ya i have a aem fuel rail aem fuel reg vortech fmu rc 310s and a vafc.i hope this will be enough to get tuned.ill keep u posted

[danl]

Why stop at 10.5:1? Why not run 13:1 compression and 2 psi of boost? I mean really, the purpose of turbocharging it so increase dynamic compression so if you want to get a woody just think about all that dynamic compression you are making at decen boost levels. However, unlike mechanical compression, intercooled boost (dynamic compression) can be cooled via an intercooler. Cooler air provides a denser air/fuel mixture. A denser charged does what? You guessed it, makes more power.

And I don't want to hear anything about the "driveability" issues with lower compression. Its really not an issuse actually. What is an issue is detonation under boost when you want to run pump gas with uber high compression and boost. I'm at 7.8:1 compression on a car with less cubic inches per pound than most any d series powered car. My friends d series turbo crx has 8.5:1 compression. We both have ample torque to go up hills at 2000rpm's in 5th gear if need be.

To answer your question. YOu will need full contron over fuel and timing management to make that combination daily driveable.

[kyosoeg6]

Why stop at 10.5:1? Why not run 13:1 compression and 2 psi of boost? I mean really, the purpose of turbocharging it so increase dynamic compression so if you want to get a woody just think about all that dynamic compression you are making at decen boost levels. However, unlike mechanical compression, intercooled boost (dynamic compression) can be cooled via an intercooler. Cooler air provides a denser air/fuel mixture. A denser charged does what? You guessed it, makes more power.

And I don't want to hear anything about the "driveability" issues with lower compression. Its really not an issuse actually. What is an issue is detonation under boost when you want to run pump gas with uber high compression and boost. I'm at 7.8:1 compression on a car with less cubic inches per pound than most any d series powered car. My friends d series turbo crx has 8.5:1 compression. We both have ample torque to go up hills at 2000rpm's in 5th gear if need be.

To answer your question. YOu will need full contron over fuel and timing management to make that combination daily driveable.


im planning running on 7lbs cus thats what the turbo gives me with no boost controller.and i really dont plan on getting one either.and the reason for the high compresion is cus i have seen numerous people run like 8.5 or lower and try running like 20lbs and it doesnt work cus of detonation.and when ever u are running that much boost there will be more chance of breakage and more wear on ur turbo when u could get the same results if not better at 10.5comp and 7lbs.

[kommon_sense]

Why stop at 10.5:1? Why not run 13:1 compression and 2 psi of boost? I mean really, the purpose of turbocharging it so increase dynamic compression so if you want to get a woody just think about all that dynamic compression you are making at decen boost levels. However, unlike mechanical compression, intercooled boost (dynamic compression) can be cooled via an intercooler. Cooler air provides a denser air/fuel mixture. A denser charged does what? You guessed it, makes more power.


this doesn't make any sense. Remember that static compressoin is a big variable in the equation when calculating dynamic compression. Besides, you can't run 13:1 w/pump gas *WITHOUT* a turbo. As for cooling the charge, remember that an intercooler can't cool the charge any cooler than ambient temperatore. So if it is 100deg outside, then guess what, it can't cool any better than that, but it will actually be quite a bit hotter due to the turbo heating up the charge.


And I don't want to hear anything about the "driveability" issues with lower compression. Its really not an issuse actually.


You think so? Higher compression gives you more off the line torque before the turbo kicks in. This may not be a big issue on a strip car, but is important on a daily driver. Also, higher compression will help the turbo to spool quicker.

What is an issue is detonation under boost when you want to run pump gas with uber high compression and boost. I'm at 7.8:1 compression on a car with less cubic inches per pound than most any d series powered car. My friends d series turbo crx has 8.5:1 compression. We both have ample torque to go up hills at 2000rpm's in 5th gear if need be.


You must live in kansas. Most civics have a hard time pulling up a hill in 5th with stock 9+:1 compression.


To answer your question. YOu will need full contron over fuel and timing management to make that combination daily driveable.

Now, question for you is, what do you actually do with your car? How much boost are you running? Is this a daily driver? You drive normally or redline every gear? Why did you go 7.8:1 CR? What fuel are you running? HOw much tuning hav eyou done? How much power are you making?

[kyosoeg6]

Why stop at 10.5:1? Why not run 13:1 compression and 2 psi of boost? I mean really, the purpose of turbocharging it so increase dynamic compression so if you want to get a woody just think about all that dynamic compression you are making at decen boost levels. However, unlike mechanical compression, intercooled boost (dynamic compression) can be cooled via an intercooler. Cooler air provides a denser air/fuel mixture. A denser charged does what? You guessed it, makes more power.


this doesn't make any sense. Remember that static compressoin is a big variable in the equation when calculating dynamic compression. Besides, you can't run 13:1 w/pump gas *WITHOUT* a turbo. As for cooling the charge, remember that an intercooler can't cool the charge any cooler than ambient temperatore. So if it is 100deg outside, then guess what, it can't cool any better than that, but it will actually be quite a bit hotter due to the turbo heating up the charge.


And I don't want to hear anything about the "driveability" issues with lower compression. Its really not an issuse actually.


You think so? Higher compression gives you more off the line torque before the turbo kicks in. This may not be a big issue on a strip car, but is important on a daily driver. Also, higher compression will help the turbo to spool quicker.

What is an issue is detonation under boost when you want to run pump gas with uber high compression and boost. I'm at 7.8:1 compression on a car with less cubic inches per pound than most any d series powered car. My friends d series turbo crx has 8.5:1 compression. We both have ample torque to go up hills at 2000rpm's in 5th gear if need be.


You must live in kansas. Most civics have a hard time pulling up a hill in 5th with stock 9+:1 compression.


To answer your question. YOu will need full contron over fuel and timing management to make that combination daily driveable.

Now, question for you is, what do you actually do with your car? How much boost are you running? Is this a daily driver? You drive normally or redline every gear? Why did you go 7.8:1 CR? What fuel are you running? HOw much tuning hav eyou done? How much power are you making?

this guy knows what im trying to get at

[kommon_sense]

if this is a daily driver setup, then you may really want to look into dropping the CR just a bit. Maybe 10:1, but 10.5:1 should still be doable with proper fuel.

[kyosoeg6]

well for now my set up will be about 9.9-10.0.when i get my head back its going to be a y8 so then it will be about 10.5

[kommon_sense]

You could always just add a thicker head gasket. Lower it down a little closer to 10:1.

[danl]

this doesn't make any sense. Remember that static compressoin is a big variable in the equation when calculating dynamic compression. Besides, you can't run 13:1 w/pump gas *WITHOUT* a turbo. As for cooling the charge, remember that an intercooler can't cool the charge any cooler than ambient temperatore. So if it is 100deg outside, then guess what, it can't cool any better than that, but it will actually be quite a bit hotter due to the turbo heating up the charge.


I was being sarcastic in parts of my statement.




You think so? Higher compression gives you more off the line torque before the turbo kicks in. This may not be a big issue on a strip car, but is important on a daily driver. Also, higher compression will help the turbo to spool quicker.


D16’s have good low rpm power for daily driving. You don’t need to spin tire when taking off. If you size a turbo properly, you can make meaningful boost around 3000rpm’s and still have plenty of breathing up top. Think factory turbocharged cars such as VW 1.8 Turbos. They have ample low end torque, and they are extremely heavy with only 200cc’s more displacement than a 600lbs lighter Crx Si for example.



You must live in kansas. Most civics have a hard time pulling up a hill in 5th with stock 9+:1 compression.


I live in Pennsylvania, Appalachian mountains.




Now, question for you is, what do you actually do with your car? How much boost are you running? Is this a daily driver? You drive normally or redline every gear? Why did you go 7.8:1 CR? What fuel are you running? HOw much tuning hav eyou done? How much power are you making?

I have a DSM, but have a lot of fun turboing Hondas to perform great on the street. I try as hard as I can to copy what the Mitsubishi engineers did with their vast resources. My car has 7.8:1 compression stock. I run a 16g turbo at 22 psi, its my daily driver. That is similar to a 60 trim T3 in garret terms. I make meaningful boost at as little as 2000rpm’s. No doubt, its because of the extra displacement I have over a 1.6L motor, but I hope you can still see my case. Pulling up hills in 5th gear making a little boost to assist is no problem. When I really want to open things up, I have 22psi of boost from 3000rpm’s on. I don’t redline every gear every time as I would quickly be breaking laws and passing people at very unsafe speeds. I do however stretch the cars legs on a regular basis when it is safe to do so.

I am just trying to demonstrate how there is more than one way to turbo a car and the pluses and minuses of each. There is a consensus in the turbo Honda community that high compression and low boost on a big turbo is the way to go. Few consider running lower compression, smaller turbo that provides meaningful boost at sane rpm’s, and higher peak boost levels. It seems that a lot of people are scared of high boost but few are scared of high compression with moderate boost. The latter scares me more (tuning wise).

EDIT: I'm sorry, but 10.5:1 compression is just a TON of compression. That just scares me to death, and that is coming from someone who has no problem running past the 25 psi limit of my boost gauge at the track.

[danl]

Here are some specs that I found online really quick for the VW 1.8T:

"1.8T
150-180 hp 1.8T
Displacement: 1781cc (1.8 liter)
Compression ratio: 9.5:1
Max. power output: 150 hp @ 5,800 rpm
Max. torque: 162 lb. ft. @ 2,200-4,200 rpm
Engine management: Motronic "

Simillar size, but we'll give the benefit of the doubt and say the turbo will spool 200 rpm's later. So, you're looking at a nice fat amount of torque from 2400rpm's or so on. We all know what happens when you raise the boost by chipping the ecu of these cars, torque and hp gains are amazing. Can't really raise the boost much more if compression was 1 point higher. Now that is some daily driving torque IMO. NOw a nice 50 trim T3 turbo witha .48 ar exhaust housing should have the party started around 3000rpm's on a d16 with 9:1 compression easilly. With even moderate boost levels of 10-12 psi 200whp with great mid range power is no problem.


Now, if you want a tractor motor, maybe a JSRC is more up your alley.

[hatchback19]

VWs have torque becasue of there stroke not because of displacment. Same with V8s, thats why they can't rev as high as a Honda built motor.

[evilfred]

It seems that a lot of people are scared of high boost but few are scared of high compression with moderate boost. The latter scares me more (tuning wise).

EDIT: I'm sorry, but 10.5:1 compression is just a TON of compression. That just scares me to death, and that is coming from someone who has no problem running past the 25 psi limit of my boost gauge at the track.

It si not what i've seen here....everybody wants to lower compression....thinking it is hard to be done with stock compression...

[kommon_sense]

EDIT: I'm sorry, but 10.5:1 compression is just a TON of compression. That just scares me to death, and that is coming from someone who has no problem running past the 25 psi limit of my boost gauge at the track.

Don't forget that the b16 and b18 are 10.2:1 and 10.1:1 compression in stock form and people have no problem turbo'ing those engines with stock compression.

Sounds like you are thinking high compression high boost. That is a bad ideal. high compression low boost is a good combo with quite a few benefits. It is no worse than low compression high boost.

Also, keep in mind that one of the reasons that your factory turbo'ed DSM is running such low compression is because it is a mass market car. Meaning that it is sold to the general public, most of which wants to get in a car and go. So it won't always get an oil change when it should. It won't always get good gas like it should. It simply won't be maintained the way that a turbo car built by an enthusiast would.

[danl]

My friends crx is making 205whp on 8.5:1 compression and 6 psi. Low-end power is not an issue. I’m just basing my comments on real life experience.

My other friends d16y8 with a t-20 turbo makes boost everywhere all the time. When you can make 6 psi at 2000rpm's climbing hills is not an issue.

[spun vtec]

When the issue of driveabilty comes into play the low compression car with moderate boost is going to be more raliable than a higger compression car with lower boost. (For the simple fact that a high compression car is less reliable than a lower compression car.)
Because of less strain on the motor off of boost and also less strain on the motor wile at low boost. there is equal strain on the motor at full boost but lower cr+high boost is much easier to mantain and alot less risk of blowing up.
So i would say away from it unless you really know how to tune and want to take the risk , or its a track car and you really know how to tune.

spun

[danl]

Fuel to fire, 1.6L d16 with 8.5:1 compression rolling on gas a little before 3000rpm's.

http://www.personal.psu.edu/users/d/j/djl242/crx%20si%20turbo%20dyno.jpg

My 2.0L DSM wiht 7.8:1 compression rolling on the gas at 2000rpm's in 4th gear on the dyno.

http://www.personal.psu.edu/users/d/j/djl242/mph%20dyno.jpg

You can run some pretty agressive ignition timing at low rpm's on lower comprssion motors to help spool the turbo and make a little more low end power. I usually run it a little lean down low as well. Personal preffrence.

[kommon_sense]

When the issue of driveabilty comes into play the low compression car with moderate boost is going to be more raliable than a higger compression car with lower boost. (For the simple fact that a high compression car is less reliable than a lower compression car.)
Because of less strain on the motor off of boost and also less strain on the motor wile at low boost. there is equal strain on the motor at full boost but lower cr+high boost is much easier to mantain and alot less risk of blowing up.
So i would say away from it unless you really know how to tune and want to take the risk , or its a track car and you really know how to tune.
spun

Considering how high the dynamic compression ratio gets when running turbo, I really don't think that having a higher static compression ratio will cause any noticeable strain on the engine.

Again, plenty of people are running low-moderate boost on stock b-series engines which have > 10:1 CR without any problems whatsoever. You just have to take your time with tuning. However you should be careful with tuning any turbo setup regardless of CR. Lower CR just gives you more room for error when tuning. It is not the only way to get the job done reliably.

[green_hornet_96]

Just browsed TOO for a while...looks like his compression ratios are insane too...FI is around 10.5:1 (and he runs 27psi!), "low" compression NA is about 13:1, "high" compression NA is almost 15:1 for a y8...so there's more to it than just compression and boost, the chamber design plays a big part

[kyosoeg6]

well im running a z6 block with forged a6 pistons and a stock y8 head.i chose this cus of the better low rpm power over the z6.i noticed my car running alot better shifting about 6500-7000rpms than 7200-7700.my turbo is small its a greddy 15g pushing 7lbs.
the motor is done and i should have it running tonight or tomarrow .ill postup results when finished.im trying to schedule some dyno time before sat dec. 6 but there is alot of people in front of me due to a local race shoot out on the 6th.

[kommon_sense]

Just browsed TOO for a while...looks like his compression ratios are insane too...FI is around 10.5:1 (and he runs 27psi!), "low" compression NA is about 13:1, "high" compression NA is almost 15:1 for a y8...so there's more to it than just compression and boost, the chamber design plays a big part

Everything that I've read regarding the y8 head is that the square combustion chambers are good for reducing detonation, so you have a little more room when tuning.

[kommon_sense]

well im running a z6 block with forged a6 pistons and a stock y8 head.i chose this cus of the better low rpm power over the z6.i noticed my car running alot better shifting about 6500-7000rpms than 7200-7700.my turbo is small its a greddy 15g pushing 7lbs.
the motor is done and i should have it running tonight or tomarrow .ill postup results when finished.im trying to schedule some dyno time before sat dec. 6 but there is alot of people in front of me due to a local race shoot out on the 6th.

Good luck. Post up those dynos when you are done. Also any input on the tuning process will be much appreciated.

[kyosoeg6]

well i finally got it running but about 4days too late.i was shooting for friday so i could get at least 200 miles on it but cum to find out i had 4bent valves in cyl#1.so it ran on 3cyl and ran like shit.so i pull off the head have it cleaned up and put 4new valves(2intake 2exhaust)then my head wasnt torked right so i had water everywhere.then i take the head off agian and clean the gasket.put the head on and now my new honda water pump is cracked.so on monday i returned it and got it back today(tuesday).put it on started the car no problems.drove it out the shop and it worked.drove it about 48 miles and no problems so far.i put 86 octane on purpose so i cant boost it.i already tried and it detonated all sick at about 4800.but let me tell u it pulls hard as fuck.i should have it tuned dynoed and broken in on friday dec12.ill post up some dyno numbers and timeslips.keep in mind i reside in a shit hole that sits 4000' above the ocean so my times arnt as fast as others

[kommon_sense]

Why would you put 86 in?

[kyosoeg6]

Why would you put 86 in?

i did that so i cant boost it.if i even try it begins to detonate.im trying to put at least 300 or so miles on it before i beat the shit out of it.i have 198miles on it so far and no problems still.runs sweet as hell.i can definitely feel the extra tq from the higher compression even shifting at 3500rpm

[kyosoeg6]

i forgot to keep this updated.at about 390miles my clutchmasters disc decided to take a shit..it did so while i was at the track.i havnt had a chance to dyno it yet but this guy that i hate with a passion was calling me out,he drives a gsr drag kit 15lbs w/rods pistons and sum other stuff.his car runs slower than a stock gsr w/ 7lbs.any ways i do my burnout and i launched,pulled fuking sick then i couldnt get out of 1st gear.so i run again thinking i got cold feet or sumthing but na it happened again.but this time cuming back i couldnt get it into any gear only on a roll not at a stand still.i was really pissed cus i got the best 60' times i had ever run.(1.79,1.80).i took off the clutch and the disc was completey burned off except for about 4or 5 little squares.i have a new clutch in it now and it runs good.better actually.i think it was starting to slip before just didnt notice it.ive got 548 miles on it now and it runs very good considering i havnt got it on the dyno w/ wideband yet.

in the bottom u can see the all thats left on the disc.

[7thGear]

My friends crx is making 205whp on 8.5:1 compression and 6 psi. Low-end power is not an issue. I’m just basing my comments on real life experience.

My other friends d16y8 with a t-20 turbo makes boost everywhere all the time. When you can make 6 psi at 2000rpm's climbing hills is not an issue.

thats cuz you got tiny 15" wheels and one of the lightest cars out there that actualy looks sporty. :D just showing both sides of the coin

[kyosoeg6]

just an update. i finally made it to the track again. i got there kinda late so i couldnt find a good launch/slick psi combo. my best et of the day was 14.1@ 98mph 1.91 60'. my first time out to the track i cut a 1.8 and a 1.78 or 1.79 i dont remember. i was launching kinda high cus the slicks were at 10lbs. im happy with those time for now. there are some local shoot outs on feb 29th and idrc on feb 21st so im going to attend those and see what i can put down. im also going to get some fuel and up the boost hope fully to about 10 or 12. i got a new block on the way so if its here by the 29th i will definitely max out this car. just to get a good time. by the way the fast time locally on a d motor is a 13.1@108 mph. i know i can catch him.

and your car would be slow to if u lived at 4000ft elevation.

[beerbongskickass]

D16’s have good low rpm power for daily driving.

Bahahaha :lol: Your joking right?

My d16z6 at 9.2:1 compression blows ass at low rpms and if I ever build the motor I wouldn't go less than 9.5:1 compression.

[kyosoeg6]

D16’s have good low rpm power for daily driving.

Bahahaha :lol: Your joking right?

My d16z6 at 9.2:1 compression blows ass at low rpms and if I ever build the motor I wouldn't go less than 9.5:1 compression.

hahaha thats why i went with 10.5 comp. but if in a light car like a hatch a healthy d16 may feel a bit more tourquier than a b16 cus of the rod stroke ratio

[infinatenexus]

[quote=danl] Besides, you can't run 13:1 w/pump gas *WITHOUT* a turbo.

Care to place a bet on that?

[tzonni]

10.5 compression can be done i guess, sport compact car a little while back had a project matrix, 11.5:1 compression stock, and they ran 7 psi on it, and drove it across the country, i dont remember where they dyno'd it at, but it had a tec II engine management system in that thing so i guess tuning is key.

[kyosoeg6]

10.5 compression can be done i guess, sport compact car a little while back had a project matrix, 11.5:1 compression stock, and they ran 7 psi on it, and drove it across the country, i dont remember where they dyno'd it at, but it had a tec II engine management system in that thing so i guess tuning is key.

man any set up with a tec ll should run no matter how high comp or how much boost. well not any but as long as its tuned

[oscarmayer]

the 10.5 lbs can be ran on low boost levels. you will need a good tuner that's for sure and dreams of reaching 12lbs of boost are certainly out unles you are running race fuel. There are several factors to consider with higher compresson motors and fi systems. detonation is a big issue along with heat generated under high comp machines. my 96 civic had 10:1 and ran 10 lbs of boost good. then we stuck in a greddy 2mmk headgasket that dropped me to 9.5:1 and we upped the boost with proper tunning to 14 lbs.

[kommon_sense]

One thing to keep in mind here is that people should set their goals on a power level, not a boost level. While low CR allows you to turn up the boost, high CR allows you to make the same power with less boost. 'course its all in the tuning.

[slebidia]

10.5 compression can be done i guess, sport compact car a little while back had a project matrix, 11.5:1 compression stock, and they ran 7 psi on it, and drove it across the country, i dont remember where they dyno'd it at, but it had a tec II engine management system in that thing so i guess tuning is key.

man any set up with a tec ll should run no matter how high comp or how much boost. well not any but as long as its tuned

I don't know about that. Everyone seems to think you can run anything witht he proper amount of tuning. You can only do so much with the 91 octane we have here....

[oscarmayer]

if you guys think you can run any level of boosting with any level of compression just because you tuned your cars. your in for a very long hard road full of bumps and broken motors. There are limits to everything. more compression does help, but too much hurts with fI systems. there is no way to get around that. really, for a dialy driver, you can't keep you car tunned well enought o run over 6-7psi on 10.5:1 compression. you need to drop that down to 9.75 or even down to 9.5: levels to be safe. can it run? yea that's not the question. the question is how LONG will it last???? if this is a project car, then by all means have at it. if this is your prim and only car, you better think twice b4 trying it.

[kyosoeg6]

the 10.5 lbs can be ran on low boost levels. you will need a good tuner that's for sure and dreams of reaching 12lbs of boost are certainly out unles you are running race fuel. There are several factors to consider with higher compresson motors and fi systems. detonation is a big issue along with heat generated under high comp machines. my 96 civic had 10:1 and ran 10 lbs of boost good. then we stuck in a greddy 2mmk headgasket that dropped me to 9.5:1 and we upped the boost with proper tunning to 14 lbs.

well as of right now ive uped the boost to about 11-12lbs. not spiked it holds steady there. i adjusted the wastegate rod making it shorter on the screw. as of now i have no detonation probs but it has been cold lately. im planning on running on sunday so ill see what kind of numbers i can do. by theway all i have to tune is my street with good neighbors that wont call the cops,apexi vafc,prelude 280cc,vortec 12.1fmu.thats all. i havent had the money to dyno yet cus this local shop thinks just cus they are the only dynojet within 400miles they can charge a nut.

[oscarmayer]

you might want to think twice about your boosting levels untill you can get a wideband abd dyno. it would not be pretty to see you destroy the motor doe to improper tuning.

[BobRoss]

you might want to think twice about your boosting levels untill you can get a wideband abd dyno. it would not be pretty to see you destroy the motor doe to improper tuning.

Sound advice.