Whats needed for 350hp on 10.5 CR

[ryan95eclipse]

So I just built my engine with 8.8 CR and my friend is gonna go with 10.5 CR. I am promised a starter ebay turbo kit ( i plan to change out all parts after boosted) if i can build and boost his engine to 350hp. 420a.

Heres the plan
Eagle rods
wiseco 10.5cr pistons
acl bearings
felpro hg
arp head bolts
felpro gasket set
blah blah blah.


Hes gonna go with ###### a 16g turbo.

What could i get away with to get this turbo'd and tuned to 350hp? He wants to run around 15psi daily.

Would i need to build the head? Or can i keep it stock since it can handle 22psi stock?

Would it be just as easy but safer to build the head, run more boost and get the same power out of 8.8:1 cr?

 

[icekilla126]

15 psi on an evo III wont make 350hp

 

[clownface]

I'm thinking that what I remember is that 350hp on the 16g is pushing it's upper limits. I think it's possible but not easy or efficient. It has to be a near perfect setup and tune if I remember correctly. I'm also pretty sure 15psi on the 16g wont make 350hp.
I think what most folk would recommend would be getting a slightly larger turbo. Something like a 20g or a similar turbo.

 

[icekilla126]

Go with the best hg money can buy a believe felpro is just your average replacement gasket. Id also say go with lower compression ratio but not sure on that hopefully someone corrects me if im wrong. A 20g around 25psi should reach your hp goal with supporting mods.

 

[Calan]

I am promised a starter ebay turbo kit...Hes gonna go with a 16g turbo.

Bad idea in general. Lots of topics (and horror stories) around here about ebay 16g's, especially when it comes time to rebuild them.

What could i get away with to get this turbo'd and tuned to 350hp? He wants to run around 15psi daily.

350awhp on a 16g is certainly possible, but more difficult than people make it out to be unless you really know how to tune...especially on pump gas without any meth injection. Regardless, you are going to need more than 15psi to get there, along with the fuel to support the higher airflow and additional cooling that will be needed.

Would i need to build the head? Or can i keep it stock since it can handle 22psi stock?

The head isn't usually the limiting factor as far as airflow (with small turbos anyway), but building it will allow you to run higher RPM's with less chance of valve float.

Would it be just as easy but safer to build the head, run more boost and get the same power out of 8.8:1 cr?

If you can tune and have the supporting fuel mods, less compression and more boost is usually a better approach, since you can always run cheaper gas and less boost if needed. The higher you go with CR, the more limited you are on which fuel you HAVE to use.

EDIT: As mentioned below, 10.5 CR is up there in race gas and E85 territory. You're gonna have a hell of a time trying to get it to make power on straight pump gas with any consistency.

Go with the best hg money can buy a believe felpro is just your average replacement gasket.

People have actually had very good luck with the Felpro composite HG.

 

[Carter_95RS]

I would choose a different turbo for this personally, an hx35 or another t3 framed turbo would be a good place to start, but that's just my opinion.

With using a high CR you will have to tune much more carefully since you will battle knock. You may want to consider E85 if you have it available.

Also, you shouldn't be limited by the stock head, but you may want to add cams and cam gears to adjust the powerband.

The factory headgasket is MLS, just so you know.

 

[standard235]

10.5:1 cr is pretty much definite e85/race gas territory

 

[ryan95eclipse]

This is why i love this site, lots of replies. Well 8.8:1 is what im doing with lots of boost. he wants 350 and since i told him power is easy to be made with high compression he is on it for that.


No on the ebay 16g. i was meaning an Evo III 16g but bigger will work, wasnt too sure.

Ill talk him into building the head and going with 8.8 compression but what supporting mods would it take to reach 350hp, hes dedicated to dropping mad money into this car for a occasional driver/track car.

 

[Calan]

...i told him power is easy to be made with high compression...

I would say it's right the opposite with a boosted motor.

 

[Carter_95RS]

No on the ebay 16g. i was meaning an Evo III 16g but bigger will work, wasnt too sure.

What are your plans for a manifold? To my knowledge no company produces a 420a manifold with a MHI collector. Every manifold I have seen is set up for a t3. Are you planning on making a custom manifold or running an adapter to go from a t3>MHI flange and deal with the possible exhaust leak and extra spacing of the turbo?

 

[ryan95eclipse]

Im still new to all see but i made out what you said. and im not sure exactly that would be one of the problems coming down the line. he would ###### get the ram horn style manifolds if not have some made up.

by easy power i ment, i was told you could use a smaller turbo and get the same results plus spool faster with less lag.

 

[Carter_95RS]

If you are planning on using the OBX ram horn you may want to read up on the threads here, it has some fitment issues. I believe the main one is contact or near contact with the thermostat housing.

 

[BigBeans]

Why did you decide on 10.5 compression for what i'm assuming is a pump gas motor?

If you're running E85 that's fine, but on pump with any decent boost level you're looking at single digit timing to keep it together.

 

[ryan95eclipse]

Well nothing if for sure as of right now, im just looking to get some ideas of what would be needed to push 350hp. So like some peoples set ups.etc

The 10.5 CR was decided after i read that it tends to reduce turbo lag by spooling faster. And after seeing a couple people were pushing well over 400whp with the 10.5 set up

 

[Calan]

...after seeing a couple people were pushing well over 400whp with the 10.5 set up

A lot more than a couple are pushing way over 400hp on stock compression.

Low compression + lots of boost = go very fast.

 

[BigBeans]

Well nothing if for sure as of right now, im just looking to get some ideas of what would be needed to push 350hp. So like some peoples set ups.etc

The 10.5 CR was decided after i read that it tends to reduce turbo lag by spooling faster. And after seeing a couple people were pushing well over 400whp with the 10.5 set up

A setup like that is great with high octane fuels, but i wouldn't recommend it on pump gas.

You'd be better off going more conservative with the compression and running more boost. You seem to think that trying to make the power with compression instead of higher boost pressures will be a safer way to do it, when in reality that's not the case, if anything it's the other way around.

If you're concerned with spool and off boost power maybe thinking about going 9:1, which is on the higher side of pump gas motors.

 

[darthvadar tsi]

change the turbo youll regret having an ebay turbo when you get boost leaks and spikes and nothing good from it. Also what bigbeans said too.

 

[Slo2gen]

I had a S25g with 10.5:1 static compression and was running 18psi and made 415whp.( http://dl.dropbox.com/u/5658928/Dyno Pics/Zac 18psi wafr.jpg ) You should get at least a 20g for sure. 16g will work but won't be the most efficient set up. And yes I was running E85, you will probably need to run something similar to get the same results...

 

[ryan95eclipse]

Ok today i talked to him a little bit about looking into finding pistons in the 9. compression area if he wants a little more power but were mostly gonna do 8.8:1 and boost the hell out of it, We made a trip to toledo and bought the car today, as soon as i get mine back together ( damn bent valve) which should be starting tomorrow im gonna start to rip his apart.


What all was used to run that much power?
20g and up turbo
walbro 255lph
megasquirt
fmu or sfmu
injectors?

A couple ideas would be better then taking a shot in the dark.

Thanks for all the help so far!

 

[Shake_Zulla]

Ok today i talked to him a little bit about looking into finding pistons in the 9. compression area if he wants a little more power but were mostly gonna do 8.8:1 and boost the hell out of it, We made a trip to toledo and bought the car today, as soon as i get mine back together ( damn bent valve) which should be starting tomorrow im gonna start to rip his apart.


What all was used to run that much power?
20g and up turbo
walbro 255lph
megasquirt
fmu or sfmu
injectors?

A couple ideas would be better then taking a shot in the dark.

Thanks for all the help so far!

Well since you seem to know a little about proper ways to plan for power I will take the time to teach you what you need to know to hit a HP goal (I hate it when people ask how to get to 20psi... its not about psi its about hp). First of all 350hp can be reached at different psi based on fuel used, temp of air, and fuel map. So I will give you a formula you can plug all your info into so you can see what you need.

First formula looks like this:
X=hp * Y * B/60

X - This will be your airflow (actual) and is needed to calculate psi
HP - This is your target HP
Y - is your air to fuel ratio
B - is your brake specific fuel consumption (BSFC)

Now the BSFC is kinda hard to figure. This is where your fuel map and injector size comes in but basically is looks like this BSFC = lb/hp * hr and then in the formula above you divide it by 60 to convert from hour to min. A safe base to guess from is .5 to .6 so I would stick to the .5 just to make sure you hit your goal.

Ok lets plug your numbers in:
X= 350 * 12 * .5/60
X = 35 (rounding up/greater BSFC will yeild greater number)

Ok so 35 is your actual airflow needed now we go to this formula to calculate psi needed.

X * G(460 + T) =P
E * rpm/2 * C

P = PSI needed (total)
X = actual airflow (see above)
G = Gas Constant = 639.6 (don't ask me how I got this number)
T = Intake manifold temp
E = Volumetric efficiency
rpm = rpm stupid
C = Engine displacement

So you have the gas constant but you need to know your Intake mani temp because cool air compresses better than hot air. If you run an intercooler usually its 100 to 130 degrees F, without one you will see 175 to 300 degrees. So lets say you have an intercooler and guess its cooling the air to 130 degrees. Now you need the Volumetric efficiency of your head. Now 4 valve per cylinder engines can run 95 to 99% efficient and the 420A had a bitchen head on it, however, these are numbers off a BRAND NEW head no buildup of any kind. Lets say you go through the head and clean it out but its still old, I would guess your at about 95%. Engine displacement = 2.0l * 61.02 = 122. so lets plug it in.

35 * 639.6 (460 + 130) = P
.95 * 7000/2 * 122

And you get 33psi... Holy crap thats a lot! Does that sound right to you? Haha one more step needed. See this is the TOTAL psi needed. We don't live in a vacuum right? At sea level we are at 14.7psi so we need to subtract this (You can calculate for your elevation I dont know/care where you live). Tada total psi we must run for 350hp at these values are just over 18 psi. So then I would calculate a 2 psi loss between compressor and cylinder and would try to hit 20psi at these values. See now how little things like air temp, air to fuel and fuel maps can effect total hp? Also I believe this equation is at a comp rate of 10:1 so if you drop to a 8.8:1 then you might want to calculate an extra 5% HP wanted... should have done that for you but I'm tired now and my brain needs to rest. Maybe some other member can go over how to choose trim rates and turbo size or point him in the right direction.


Edit: Just to show you how important cold air is, if you drop from 130 degrees to 100 degrees you can achieve the same hp (350) with 3 less psi (17psi calculating a 2psi loss).

 

[Carter_95RS]

Very good explination, Jared.

 

[Calan]

I'm all for theory (and that is some very good info), but getting 350hp out of a boosted 10:1 CR motor with a 16g/20g @ 20psi on pump gas is a hell of a lot harder than that makes it sound.

Unless I'm just brain dead today (highly possible), you are calculating for HP at the crank; if you want true awhp (which most people are talking about when we consider HP), you also need to consider drivetrain losses. That would put your example target HP number somewhere around 410-430 (I'm guessing, depending on which drivetrain), which dramatically changes what you can do with a small turbo at that CR.

On pump gas, you will be severely knock-limited long before you can hit the required boost to make 350 at the wheels on that setup.

 

[Shake_Zulla]

I'm all for theory (and that is some very good info), but getting 350hp out of a boosted 10:1 CR motor with a 16g/20g @ 20psi on pump gas is a hell of a lot harder than that makes it sound.

Well all you have is theory untill you slap your specific car on a dyno. Sorry if I made this sound easy because it isn't. First (and hardest) thing needed to do is to figure out your BSFC. I was just trying to show a semi-effecient way of getting to 350hp. You don't need a high BSFC or even an intercooler to achieve 350hp, however, you will need to run a way higher PSI. Mainly I was trying to show how several things effect hp not just compression rates and PSI.

 

[Calan]

Well all you have is theory untill you slap your specific car on a dyno. Sorry if I made this sound easy because it isn't. First (and hardest) thing needed to do is to figure out your BSFC. I was just trying to show a semi-effecient way of getting to 350hp. You don't need a high BSFC or even an intercooler to achieve 350hp, however, you will need to run a way higher PSI. Mainly I was trying to show how several things effect hp not just compression rates and PSI.

Don't get me wrong... that is some very good info you posted.

(edited my post BTW)

 

[Shake_Zulla]

I'm all for theory (and that is some very good info), but getting 350hp out of a boosted 10:1 CR motor with a 16g/20g @ 20psi on pump gas is a hell of a lot harder than that makes it sound.

Unless I'm just brain dead today (highly possible), you are calculating for HP at the crank; if you want true awhp (which most people are talking about when we consider HP), you also need to consider drivetrain losses. That would put your example target HP number somewhere around 410-430 (I'm guessing, depending on which drivetrain), which dramatically changes what you can do with a small turbo at that CR.

On pump gas, you will be severely knock-limited long before you can hit the required boost to make 350 at the wheels on that setup.

True, true you have me there I was going for crank HP. Also I have a theory that dyno's arn't as acurate as people believe... but I want to run that by a few people smarter than me before I look like a fool. Your 410-430 guess seems a bit high... maybe because you have an AWD . I would guess lower for a FWD and a MT I know our drive chain isn't horrible but I'm not an expert. As for the pinging obviously at that high of HP you are going to be better off with a stand alone unit where you could advance the spark timing. After all HP would be easier to gain with more control of your fuel and spark. Overall this is a great conversation and I would like to point out also that CP rate will only effect HP by 4% across the board between a 10:1 and a 8.8:1

Thanks for remaining civilized through this discussion Calan its a quailty not seen as much in the forum world.

EDIT: Just ran the numbers a 15 to 20% power loss actually sounds right sorry