I am going to be running Gt28 turbo on built LS bottom and Built Gsr head ...

8 to 1 comp pistons

stock sleeve, what PSI can i run on stock sleeve? will be daily driver

would like 350 HP
BUT
looking at target of 300HP

 

sup bro im pushing 15psi on my ls vtec ek and work a twalnut creek. stock ls sleeves with built gsr head 8 to 8 wiseco pistons

 

check me out in action

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by g0tgot &raquo;</TD></TR><TR><TD CLASS="quote">I am going to be running Gt28 turbo on built LS bottom and Built Gsr head ...

8 to 1 comp pistons

stock sleeve, what PSI can i run on stock sleeve? will be daily driver

would like 350 HP
BUT
looking at target of 300HP</TD></TR></TABLE>

Take the psi question out of the equation and focus on the 300 to 350 hp target. For a properly tuned forged & built LS-V-T, 300 to 350 hp is a walk in the park on stock sleeves, but your turbo size is gonna dictate how many psi will get you there, so dont base it on that.

But for the record, I've see some 400 to 500 hp stock sleeve boosted B motors.

 

Its pretty easy to work out math wise.

Stock ls/vtec 140hp
Hp Required 350hp
Difference = 160hp

(140+210 / 140) -1 = 1.5 or 150% increase in hp

You can use use that 1.5 ratio multiply atmospheric pressure (14.7)

1.5 x 14.7 = 22.05 psi in order to produce your required power. Yes that is just the very rough math in working out you basic requirements in order to achieve your requirements. VE, Air temp, Barometric pressure, *Turbo Efficiency* will all play a big part but that will put you in the ball park.

The key thing in making a stock block survive is tuning and the freeing up of horsepower. Detonation and preignition will destroy a stock block no matter what you have done. Also by increasing VE of the engine you are able to decrease boost pressure on the engine which will reduce stress but still maintain your horsepower levels. But overall what you are shooting for can be done pretty easy.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by steven_highet &raquo;</TD></TR><TR><TD CLASS="quote">Its pretty easy to work out math wise.

Stock ls/vtec 140hp
Hp Required 350hp
Difference = 160hp

(140+210 / 140) -1 = 1.5 or 150% increase in hp

You can use use that 1.5 ratio multiply atmospheric pressure (14.7)

1.5 x 14.7 = 22.05 psi in order to produce your required power. Yes that is just the very rough math in working out you basic requirements in order to achieve your requirements. VE, Air temp, Barometric pressure, *Turbo Efficiency* will all play a big part but that will put you in the ball park.

The key thing in making a stock block survive is tuning and the freeing up of horsepower. Detonation and preignition will destroy a stock block no matter what you have done. Also by increasing VE of the engine you are able to decrease boost pressure on the engine which will reduce stress but still maintain your horsepower levels. But overall what you are shooting for can be done pretty easy.</TD></TR></TABLE>

Now take that pressure ratio, and mate it to the GT28R and find the lbs/min you get. You'll notice that it will be almost out of its efficiency range for it to work. You'll need to upgrade your turbo size a bit, and recalculate. Your VERY low static compression will require even more boost to get the power you need, and will actually hurt your acceleration rate. Increase your static compression up to about 9.1 to 9.5 to get that acceleration back.

 

no wonder my acceleration feel slow. I'm at 8:8 pistons in ls block with gsr head 81.5mm

 

Stock sleaves will eat up 350whp for a joke, good tune is the key. BTW dont buy those pistons, they are damn near useless, 8:1 compression is LOW LOW, youll have no ***** before boost. 9.5:1 compression is a perfect balance, hell there are stock block 11:1 k20's making over 500whp, its all in the tune, just remember that. Because you could sleave your block with BP M1's and use the strongest rods and pistons, with a shitty tune none of that means a damn.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheShodan &raquo;</TD></TR><TR><TD CLASS="quote">

Now take that pressure ratio, and mate it to the GT28R and find the lbs/min you get. You'll notice that it will be almost out of its efficiency range for it to work. You'll need to upgrade your turbo size a bit, and recalculate. Your VERY low static compression will require even more boost to get the power you need, and will actually hurt your acceleration rate. Increase your static compression up to about 9.1 to 9.5 to get that acceleration back.</TD></TR></TABLE>

Yip yip!!

Size your turbo around your required boost in order for the pressure ratio and lbs/min to sit right in the middle of the efficiency island. One of my best sayings at work is " Work smarter not harder" and that relates to turbo sizing to. Sizing a turbo to your requirements reduces intake temps and allows the turbo to create boost alot more efficiently which will allow you to use less boost to generate the same HP.

Now when it comes to compression ratio one is not better than the other. Its all depends on you. Hp or Reliability? Yes 9.5 is safe but 8.5 is safer. Shodan is def right go with about 9.1 it is a good median between the two.

 

I was running my eg with ls/vtec on a turbonetics 62-1 turbo with 10.0:1 compression and I daily drove it for a little over a year. It was pushing around 450whp...sleeves cracks last month

 

wow great info guys!

 

140+210 / 140) -1 = 1.5 or 150% increase in hp========i see 140 for HP where did the 210/140 come from?

also the turbo kicks in at about 3K im not really worried about the sluggish start off, i dont know anyone who revs at 3k...i guaruntee i will be shifting into boost...with the CTR valvetrain ill have a good high rev and boost should be ok....but maybe i will upgrade at a later date, this looks good for my first turbo build dont want to over do it, start off small and work my way up....i need to gain some experience here.

 

You'll gain that experience, alright. But you've also received input from a few us that have been doing this over 10 years, so you may want to NOT ignore them by simply stating what you already know. When the pressure ratio is raised by your lower compression to get the same lbs/min, you'll see a major difference regardless of your definition of "boosting" under 3Krpm. An efficient turbo setup really is where you don't NEED to downshift 1 or even 2 gears to get into your acceleration. As someone else stated on here (I believe it was steven_highet), why work harder when you can build smarter?

Just a thought

 

ok thanks shodan, i am trying to work around the 8 to 1 comp pistons because unfortunatly i allready got them with the build but, so what would be the best recomendation for a size turbo with the 8-1 comp?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by g0tgot &raquo;</TD></TR><TR><TD CLASS="quote">140+210 / 140) -1 = 1.5 or 150% increase in hp========i see 140 for HP where did the 210/140 come from?</TD></TR></TABLE>

here is the formula.

Current HP + Required HP to achieve your goal / Current HP -1 = ?

The reason you divide by your current HP is to work out the ratio in comparison to your original mechanical HP figure.

Listen to Shodan!! These guys have been doing this a very long time they have been down the road you are going. Nothing is worse than putting together a build and learning so much info over time that you need to buy new parts in order to achieve what you want cause your original build is just not cutting it. You may already have your pistons but that doesnt lock you into them. What Shodan said is so so true "Build Smart". Analize every thing about what you are going to do. Any body can bolt **** togother and go boosting but its the small things that are gonna make your setup last. I am a low compression person but 8:1 is extreme!

It will be kinda hard to work out your turbo size on compression. Flow is calculated using VE, Displacement and Rpm. You can take compression into consideration when viewing compressor maps but but will not be able to plot it. A T3/T4oe 60 trim will get you in the ball park on what you need.

 

ok so i called the dude, i am going to try to find pistons and turbo, ideal here is im loking at A T3/T4oe 60 trim and 9.5-1 pistons......let me know if this is ideal and WHERE i can find a turbo like that for around or under $600 new if possible

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by g0tgot &raquo;</TD></TR><TR><TD CLASS="quote">ok thanks shodan, i am trying to work around the 8 to 1 comp pistons because unfortunatly i allready got them with the build but, so what would be the best recomendation for a size turbo with the 8-1 comp?</TD></TR></TABLE>

If you already have the pistons then you can mill the head to get some compression back. Mill the head about .030 to bump you up closer to 9:1. This is assuming your head has not been milled before.

 

i took out pistons today, i have found these pistons that are like 9.8 to one, kinda off but these should be alot better than the 8-1 i am assuming....maybe if i get thicker headgasket i can lower comp to 9.6 toi 1 then ill be good to go...or maybe just use stock GSR.....i cant find 9.5 to one out where i live, unless someone wants to trade me for 8to1.......

 

i just had my LsVtec-T tuned w a Gt30r on stock sleeves w a built head and block and i hit 350 on the dyno. well for a street driven car it is a fun ride!!!!!! 12 ibs btw

 

nice.. cant wait to get my car .... still waiting for head from machine shop.... then ill be good to drop in and go!