Boost Limit Reached on 10:1 Compression
05-14-2005, 09:01 PM
#21
Originally Posted by stevieturbo
Mines a speed density setup. When I first got it running with boost, I had the timing up closer to 18deg at that part of the map, and it was pinking like mad. I had to drop it back to kill the det. I would be getting about 18 deg in the midrange, but boost pressure then is only about 3psi climbing
Im not monitoring fuel pressure, but see no reason why it would be an issue. AFR's are steady in the low 11's. I could easily drop them to 10's if I wanted ( and had done during setting up ), or lean them off. Keeping them in the 11's for safety.
A1000 feeding 1/2" solid alu pipe feeding the Aeromotive rails via a fuel dist block.
Charge air temps are measured in the pipework just before the TB, and I have no reason to doubt their accuracy.
Exhausts are 3" collectors, stepping down to 2 1/2" with a balance pipe between them on the 2.5" section. 2 x 2 1/2" Magnaflow straight through silencers.
Eventually I will swap to 3" from headers to exit.
What sort of timing are other 10:1 CR pump fuel only, boosted motors using ?
can you plot a table of map vs rpm for timing ? The ve tables on the stock ecu dont mean that much to me.
Im not monitoring fuel pressure, but see no reason why it would be an issue. AFR's are steady in the low 11's. I could easily drop them to 10's if I wanted ( and had done during setting up ), or lean them off. Keeping them in the 11's for safety.
A1000 feeding 1/2" solid alu pipe feeding the Aeromotive rails via a fuel dist block.
Charge air temps are measured in the pipework just before the TB, and I have no reason to doubt their accuracy.
Exhausts are 3" collectors, stepping down to 2 1/2" with a balance pipe between them on the 2.5" section. 2 x 2 1/2" Magnaflow straight through silencers.
Eventually I will swap to 3" from headers to exit.
What sort of timing are other 10:1 CR pump fuel only, boosted motors using ?
can you plot a table of map vs rpm for timing ? The ve tables on the stock ecu dont mean that much to me.
What are the specs on your cam, that could be a difference also.
You wont find any other cars on this forum running the kind of boost that I am running on 10:1 CR on pump gas. I stand alone in that crowd. The only difference I can think of between mine and yours is I do have a 427 CI motor.
05-14-2005, 10:05 PM
#23
Originally Posted by stevieturbo
mail sent...thanks, Stevie
05-15-2005, 10:12 AM
#25
Originally Posted by Bryan Wilkinson
just like it was said 71# injectors would not be able to deliver enough fuel and by the way, they are in the low 80% DC range.
just like it was said that you could not make 800RWHP on pump gas, and by the way, I make 800RWHP on 14.5PSI at 6000, and it will run all day.
just like it was said that you could not make 800RWHP on pump gas, and by the way, I make 800RWHP on 14.5PSI at 6000, and it will run all day.
i dont think its fair to put the notion in peoples mind that 800 is possible and reliable by your results.. you just blew a 2nd head gasket remember? this was on a dyno in 5 seconds in one gear.. imagine all 4 gears plus a burnout at the dragstrip...
in all fairness i could probably hit 800rw on pump gas only while blowing a head gasket
i'll 'settle' for 900rw on methanol and not be replacing head gaskets between rounds.no air filter... sounds like a street car!
im just givin ya **** man. good luck to being back on the road w/ the right compression for the task. thanks for being honest with us.. a LOT of people get or give the wrong idea on here because they leave out the bad.
130* intake temp in one gear is high, mabey you need to up the intercooler?
05-15-2005, 03:21 PM
#26
Originally Posted by Bryan Wilkinson
I did notice in your signature about your dual exhaust and can tell you, that even though you would not think so, a single 3.5" will outflow the duals.
05-15-2005, 03:38 PM
#27
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It sounds like you have one hell of a curosity. I would like to see what you could get with a good methanol injection system. Its still a street car if you have to add methanol to make it run. Just think of the methanol like adding oil, gas, or transmission fluid 
05-15-2005, 07:35 PM
#29
Originally Posted by smokinHawk
id definatly be worried about your motor, if your blowing gaskets with an unloaded dyno image when you run it down the track or street, snap crackle pop!
will the 4psi your backing it down be enough?
will the 4psi your backing it down be enough?
The awesome thing here is that I was able to hit the 822 mark successfully and consistently on 16PSI on pump gas, without detonation or knock.
05-15-2005, 07:46 PM
#30
Originally Posted by MIGHTYMOUSE
speed inc made 844rw w/ 60# injectors last fall just for those who were doubting your 71's.
i dont think its fair to put the notion in peoples mind that 800 is possible and reliable by your results.. you just blew a 2nd head gasket remember? this was on a dyno in 5 seconds in one gear.. imagine all 4 gears plus a burnout at the dragstrip...
in all fairness i could probably hit 800rw on pump gas only while blowing a head gasket i'll 'settle' for 900rw on methanol and not be replacing head gaskets between rounds.
no air filter... sounds like a street car!
im just givin ya **** man. good luck to being back on the road w/ the right compression for the task. thanks for being honest with us.. a LOT of people get or give the wrong idea on here because they leave out the bad.
130* intake temp in one gear is high, mabey you need to up the intercooler?
i dont think its fair to put the notion in peoples mind that 800 is possible and reliable by your results.. you just blew a 2nd head gasket remember? this was on a dyno in 5 seconds in one gear.. imagine all 4 gears plus a burnout at the dragstrip...
in all fairness i could probably hit 800rw on pump gas only while blowing a head gasket
i'll 'settle' for 900rw on methanol and not be replacing head gaskets between rounds.no air filter... sounds like a street car!
im just givin ya **** man. good luck to being back on the road w/ the right compression for the task. thanks for being honest with us.. a LOT of people get or give the wrong idea on here because they leave out the bad.
130* intake temp in one gear is high, mabey you need to up the intercooler?
First let me congratulate you on your accomlishments. I think you have an impressive setup.
Thank you for not slamming the door in my face. That means a lot.
I feel pretty certain that I am not blowing gastets because I am running pump gas. I am blowing gaskets because of the amount of boost I am running on 10:1 compression as you mentioned. I dont think Methanol would have helped here.However I do feel pretty certain the weak Cometic Gasket in this case continues to be the life saver.
The new pistions are set to 9.5:1 when using the new Oliver 6.125" rods that I have purchased for my winter conversion. The biggest pull that was consistant without blowing anything has been 17.6 PSI. That is not to go without saying that it was extreme for this application.
I consider this a lesson learned. When I started all of this it was never my intention to be where the car is today and certainly was no intention to have it where I want to go with it.
I will continue to learn and share my experiences so that others may avoid those pitfalls.
I will get it to the track eventually. It is just not cheap experimenting like this
05-15-2005, 08:15 PM
#31
It's good to see someone testing out there setup to the max.Here is a few thought's.
10-1 compression with 18lb's = I see 19 degree's of timing being way too much on the top end. (My N/A 408's only run 20 degree's -530rwhp) There are 2 reasons head gaskets pop. 1- Too much timing ,,2-Too lean.
10-1 compression with 18lb's = I see 19 degree's of timing being way too much on the top end. (My N/A 408's only run 20 degree's -530rwhp) There are 2 reasons head gaskets pop. 1- Too much timing ,,2-Too lean.
05-15-2005, 09:43 PM
#32
i know you like doing your own thing, and thats what it takes sometimes to progress.. but from behind my stack of broken pistons let me tell you DO run below 8.5:1 at this power level on 93 octane and DO run some methanol to control the detonation.. it will save your *** if not now then later.
05-16-2005, 04:51 AM
#35
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Originally Posted by Slowhawk
It's good to see someone testing out there setup to the max.Here is a few thought's.
10-1 compression with 18lb's = I see 19 degree's of timing being way too much on the top end. (My N/A 408's only run 20 degree's -530rwhp) There are 2 reasons head gaskets pop. 1- Too much timing ,,2-Too lean.
10-1 compression with 18lb's = I see 19 degree's of timing being way too much on the top end. (My N/A 408's only run 20 degree's -530rwhp) There are 2 reasons head gaskets pop. 1- Too much timing ,,2-Too lean.
I completely agree with this, too much cylinder pressure, which is caused from being too lean and/or too much timing.
I also think 3.5" single pipe is a restriction, have you ever tried running open headers with extensions to see a power difference? and or boost loss..... from what I have read 4" is good for 900 fwhp.
straight pipe 2 2.5" peices have the area of 9.8" sqaure inches and a single 3.5 has 9.6" so Id go with the dual 2.5s my single 4" flows as much as 2 2.75" pipes but not dual 3"
lowering your compression will only lower cylinder pressure, unless the supercharger runs more efficient are a higher rpm or the motor wants to be at a specific timing, I dont see the compression being a limitation.
I really think you have found the limitation of pump gas with your setup. someone mentioned you need to cool your IATs it does sound like you need a better intercooler, temps are waaay over ambient. once you cool that down power should go up.
just some of my thoughts. Awesome car, very inspirational to a lot of people for sure
if you wanted to gain some power at the same boost level go turbo, I bet that belt driven blower is zapping 75-100 rwhp. 
05-16-2005, 11:00 AM
#36
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Deep thoughts.... by Nitro Rocket.
Bryan. You are doing a rod and piston swap. Why are you ONLY dropping to 9.5:1. .Half point does'nt seem like a very cost effective swap for the power gained. Cosidering each psi of boost gives you say 5% more power(have you figured your averagepsi/hp gain?), and each point of compression gives you roughly only 3% more power, would'nt it make sense to drop down to 8:1 compression based on your pumpgas power quest?
You might possibly want to reconsider your compression for your long term no additive max pumpgas power goals. I have a similar goal and will be doing some experimenting in a few weeks when I get my motor running. I chose to go with 8.0:1 and actually ended up with 8.1:1(not like .1 or .2 will make a world of difference). I would have went lower, But Dutweiler recommended for my application to not drop below 8 being that with a turbo setup, you need some amount of compression to create enough velocity to help spool the turbos up without having to go to small on the A/R ratio.
You might even benifit with lets say 7-7.5:1, with being a supercharged setup and not having to worry about turbo velocity problems. Especially being you have such a large (427) motor. Again, I am saying this based on you max pumpgas power goals. This would allow you to maximize your boost power differential and possibly hit much more then 900 rwhp.
Setup questions??
-What size inlet pipe and filter are you running, sounds like you need much larger or possibly a dual setup.
-What rods are you switching from?
-What intercooler brand and model are you using? 130 temps are a little high. With the maxpumpgas goals, intercooler efficiency and pressure drop become very critical. I know with my setup, I ended up choosing the Spearco 2-182 intercooler. I had to custom fab my own special design intercooler tanks to minimize flow restrictions as well as blend inlet trasitions to minimize turbulance...This all adds up.
Bryan. You are doing a rod and piston swap. Why are you ONLY dropping to 9.5:1. .Half point does'nt seem like a very cost effective swap for the power gained. Cosidering each psi of boost gives you say 5% more power(have you figured your averagepsi/hp gain?), and each point of compression gives you roughly only 3% more power, would'nt it make sense to drop down to 8:1 compression based on your pumpgas power quest?
You might possibly want to reconsider your compression for your long term no additive max pumpgas power goals. I have a similar goal and will be doing some experimenting in a few weeks when I get my motor running. I chose to go with 8.0:1 and actually ended up with 8.1:1(not like .1 or .2 will make a world of difference). I would have went lower, But Dutweiler recommended for my application to not drop below 8 being that with a turbo setup, you need some amount of compression to create enough velocity to help spool the turbos up without having to go to small on the A/R ratio.
You might even benifit with lets say 7-7.5:1, with being a supercharged setup and not having to worry about turbo velocity problems. Especially being you have such a large (427) motor. Again, I am saying this based on you max pumpgas power goals. This would allow you to maximize your boost power differential and possibly hit much more then 900 rwhp.
Setup questions??
-What size inlet pipe and filter are you running, sounds like you need much larger or possibly a dual setup.
-What rods are you switching from?
-What intercooler brand and model are you using? 130 temps are a little high. With the maxpumpgas goals, intercooler efficiency and pressure drop become very critical. I know with my setup, I ended up choosing the Spearco 2-182 intercooler. I had to custom fab my own special design intercooler tanks to minimize flow restrictions as well as blend inlet trasitions to minimize turbulance...This all adds up.
05-16-2005, 11:06 AM
#37
i run a single 3.5" downpipe before the 4" muffler.. the downpipe has a 3" flange at the beginning of it. i'm fairly certain ive heard of over 1krwhp being pushed through a 3" flange before.. not to say that it was the most efficient way to get there.
05-16-2005, 11:41 AM
#39
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John Meaney's C4 is like a 400ci aluminum smallblock with twin turbos. I know very little about the car, but it's around 8:1. Car goes 135mph on pump gas and 160mph on race gas (C16).
When your IATs get high, 150+, you have to back the timing down.
Bryan, I am making 21.5 psi and am not lifting heads. Harlan made like 1000 crank with ARP head studs and a hydraulic cam...
It's your car but Brady has gone like high 8's on 93 pump, and I thought he said he was using less than 10 degrees of timing... wow.
When your IATs get high, 150+, you have to back the timing down.
Bryan, I am making 21.5 psi and am not lifting heads. Harlan made like 1000 crank with ARP head studs and a hydraulic cam...
It's your car but Brady has gone like high 8's on 93 pump, and I thought he said he was using less than 10 degrees of timing... wow.
05-16-2005, 11:42 AM
#40
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I am running 3" from the turbine housings, to the bumper. I might ditch the flowmasters though, I will have to see when I fire it up. This does'nt really apply to Bryan's Supercharged car though, although the 2.5 in tailpipes are very restrictive!