Ordered my first turbo today! GT-K 850 What you think?
#21
TECH Senior Member
iTrader: (16)
Originally Posted by BigJls1
it is [B]rear mount [/B] so alot can be learned from this guys setup, there is not alot of info on how rear mounts act with 850 hp. You must size the turbo smaller for the rear mount.
WE know this is a REAR MOUNT SET UP We have quite a few members making great power with rear mount set ups.
One is already doing a big inch big turbo set up, but hasn't updated in a while.
One thing you are not getting is the backpressure a undersized turbo will create on a big inch combo. Headgaskets will be lunched regularly.
Texas, call Jose@forcedinductions.com
www.forcedinductions.com
I'd ditch the rear mount set up altogether and go the traditional front mount route. A truck manifold set up will be easy to set up and have no worries about the drawbacks to having a rear mount....i.e. intake and exhaust plumbing share the same space under the car.
BigJLS1 post results and info on your big inch rear mount combos that you have built. I'd like to see and read about them.
#22
Originally Posted by BigJls1
with all these guys talking about you need a bigger turbo. I disagree I have done three custom rear mounts setups. Your problem is not going to be the exhaust backpressure build- up as was stated by someone that 3:1, no way, your problem will be trying to fit an intake pipe to flow 60 or 70 lbs and hour and not hang 3" below your car. Alot of folks will dump info on you but they are useing front mount turbo knowledge. You have will be suprised how different rear mount technology is. keep what you have. and use 2.5 ehaxust for now and the .81 housing. then when you go 427 I say go 3" exhaust and at least the .96 maybe even an 1.15 housing. You will need 2.5" or even 3.0" intake pipe, good luck fitting that maybe you can go with (two) 2" pipes to flow enuff and still have ground cleareance.
So no more GT-K 850. I can not wate for the Forced Induction 76GTS to get here!!!
Now I need to find out if my present injectors and fuel rail will support 500-550RWHP. I know my fuel pump will work do to the fact it is already plenty good for the nitous I am running (255 pump). I am running SVO 30 pound injectors, which I am sure I will need to change. If I change them can I go ahead and just change them to the size I will need for the 427 at 850rwhp? I am conserned they will be too big for street driving. I still need to decide on the return oil pump size and brand, which intake, and how I want to do my PCV system.
This is getting long wined, sorry.
As for the pipping, I plan on removing both of my subframe conenctors and building new ones that will be sealed, sized for the flow, and strong enough to work as subframe conectors. Y the air from the turbo discharge and pass the air down both sides of the car threw the new subframe conectors. At the front have both go under the K-member (or over or even threw, have not made up my mind yet) and then Y back together before the intercooler. All the exhaust and air piping and the intercooler is pretty much completed as far as planning goes. I like the idea of modifying the K-member to were I can pass the air threw it while still maintaning the ground clearence. Very duable I think. It might only cause .5" to 1" of ground clearence loss due to the placement of the steering. Maybe someone could take this idea and run with it.
Last edited by Texas_WS6; 08-31-2007 at 08:32 PM.
#23
Originally Posted by frcefed98
WE know this is a REAR MOUNT SET UP We have quite a few members making great power with rear mount set ups.
One is already doing a big inch big turbo set up, but hasn't updated in a while.
One thing you are not getting is the backpressure a undersized turbo will create on a big inch combo. Headgaskets will be lunched regularly.
Texas, call Jose@forcedinductions.com
www.forcedinductions.com
I'd ditch the rear mount set up altogether and go the traditional front mount route. A truck manifold set up will be easy to set up and have no worries about the drawbacks to having a rear mount....i.e. intake and exhaust plumbing share the same space under the car.
BigJLS1 post results and info on your big inch rear mount combos that you have built. I'd like to see and read about them.
One is already doing a big inch big turbo set up, but hasn't updated in a while.
One thing you are not getting is the backpressure a undersized turbo will create on a big inch combo. Headgaskets will be lunched regularly.
Texas, call Jose@forcedinductions.com
www.forcedinductions.com
I'd ditch the rear mount set up altogether and go the traditional front mount route. A truck manifold set up will be easy to set up and have no worries about the drawbacks to having a rear mount....i.e. intake and exhaust plumbing share the same space under the car.
BigJLS1 post results and info on your big inch rear mount combos that you have built. I'd like to see and read about them.
Thanks for getting me on the right track.
#24
Update.
I dropped the 427 idea all together. I do not want to wait 2 years to finish the proiect. So I am now completing the 408 I already started. I should have the shortblock back from the builder by the end of January. Putting ported L92 heads and the GM performance intake (ported) on it as well. I have not bought the cam for it yet. Waiting to see the final flow numbers on the heads intake combo. Any sugestion?
Now I am rethinking the rear mount idea as well. I would realy like to do a front mount with truck manifold. Question is, will my 76GTS work up front on the 408? What size AR will I need to go to? I realy hope the turbo will support this engine and make 800rwhp.
I have seen several truck manifold setups that use both manifolds and removes the AC. Has anyone tried using just the passanger truck manifold on the drivers side, keep the F-body passenger manifold on the passenger side, and plumb the passenger side exhaust around the transmition and back up under the drivers side exhaust to Y in before the turbo? Once the alternator is relocated, would that leave enough room for both the passenger exhaust piping and the down tube piping? Just a thought.
I dropped the 427 idea all together. I do not want to wait 2 years to finish the proiect. So I am now completing the 408 I already started. I should have the shortblock back from the builder by the end of January. Putting ported L92 heads and the GM performance intake (ported) on it as well. I have not bought the cam for it yet. Waiting to see the final flow numbers on the heads intake combo. Any sugestion?
Now I am rethinking the rear mount idea as well. I would realy like to do a front mount with truck manifold. Question is, will my 76GTS work up front on the 408? What size AR will I need to go to? I realy hope the turbo will support this engine and make 800rwhp.
I have seen several truck manifold setups that use both manifolds and removes the AC. Has anyone tried using just the passanger truck manifold on the drivers side, keep the F-body passenger manifold on the passenger side, and plumb the passenger side exhaust around the transmition and back up under the drivers side exhaust to Y in before the turbo? Once the alternator is relocated, would that leave enough room for both the passenger exhaust piping and the down tube piping? Just a thought.
#25
Your going to need a .96A/R for sure now that you are upgrading to the larger engine. You can squeek some big numbers with the turbo,but it will be out of its efficiency range at that point. Its give and take in the turbo world.
#26
TECH Senior Member
iTrader: (48)
i dont think the 76gt6 comes bigger then a .96ar which you will need bigger.
your getting a little better going down to the 408, but that engine is still a bit to big for the turbo, it will work but i guaranteed you will make more power out of a smaller engine with that turbo. is it to late to put the stock strok crank on there, if you do around 360ish cubes and that turbo spinning it to around 6800rpm with a good amount of boost that turbo will suport, you would be around 900rwhp or past
your getting a little better going down to the 408, but that engine is still a bit to big for the turbo, it will work but i guaranteed you will make more power out of a smaller engine with that turbo. is it to late to put the stock strok crank on there, if you do around 360ish cubes and that turbo spinning it to around 6800rpm with a good amount of boost that turbo will suport, you would be around 900rwhp or past
#27
i dont think the 76gt6 comes bigger then a .96ar which you will need bigger.
your getting a little better going down to the 408, but that engine is still a bit to big for the turbo, it will work but i guaranteed you will make more power out of a smaller engine with that turbo. is it to late to put the stock strok crank on there, if you do around 360ish cubes and that turbo spinning it to around 6800rpm with a good amount of boost that turbo will suport, you would be around 900rwhp or past
your getting a little better going down to the 408, but that engine is still a bit to big for the turbo, it will work but i guaranteed you will make more power out of a smaller engine with that turbo. is it to late to put the stock strok crank on there, if you do around 360ish cubes and that turbo spinning it to around 6800rpm with a good amount of boost that turbo will suport, you would be around 900rwhp or past
#28
No, I have had the crank in the gaurage for 4 or 5 years now. I hate to ditch it now.
So, if I stick with the original plan as far as the rear mount set up, would this turbo with the .96 work better with the 408? I realy do not want the turbo to come on early. I am counting on a little turbo lag to help hook the car. I have not bought the manifolds yet. I can still continue with the rear mount. I just do not like the oil pump return aspect, as well as the air inlet being under and at the rear of the car.
I am stuck with the 408, and I am not able to upgrade the turbo to a larger one at this time. So what are my options other then selling the turbo for a lose to buy a larger turbo.
What staull speed and cam size should I be thinking about? I have a 4000 staull right now. I must be getting old though, I am realy tired of all that staull.
So, if I stick with the original plan as far as the rear mount set up, would this turbo with the .96 work better with the 408? I realy do not want the turbo to come on early. I am counting on a little turbo lag to help hook the car. I have not bought the manifolds yet. I can still continue with the rear mount. I just do not like the oil pump return aspect, as well as the air inlet being under and at the rear of the car.
I am stuck with the 408, and I am not able to upgrade the turbo to a larger one at this time. So what are my options other then selling the turbo for a lose to buy a larger turbo.
What staull speed and cam size should I be thinking about? I have a 4000 staull right now. I must be getting old though, I am realy tired of all that staull.
#29
TECH Senior Member
iTrader: (48)
why not sell your crank then.
the set up will work that you have but there are allot of wasteful parts that you dont need.
and you will make more power with the turbo up front.
first you will only make as much HP as that turbo can support, next to get the most out of your turbo and to make well with your engine you should size it to the turbo and desired rpm range.
you need to ask your self how much power do you want, and then were do you want that power.
the set up will work that you have but there are allot of wasteful parts that you dont need.
and you will make more power with the turbo up front.
first you will only make as much HP as that turbo can support, next to get the most out of your turbo and to make well with your engine you should size it to the turbo and desired rpm range.
you need to ask your self how much power do you want, and then were do you want that power.
#30
I spoke with Forced Induction about the limitations and options. I had the turbo sized for the rear of the car. Moving it to the front will require a different turbo. Taking into consideration the goals and options for this build, I will continue with the rear mount set up and complete the 408. When I bought my crankshaft, they were about 300 dollars more then they are now. So selling the crank is not an option. Of anyone wants a new still in the box 76GTS turbo from Forced Induction, I will be willing to sell it to them. But at the same price I bought it. I would then purchase a turbo sized for the front and go that route. I am sure everyone will want a less then new price for the turbo, so I will have to complete the biuld as planed.
Lessons learned, never change horses mid stride.
It will still be a great build.
Lessons learned, never change horses mid stride.
It will still be a great build.