after 4 days on the dyno and 70 pulls, 90 % of my questions have been answered. But just a couple evade me. 355 ci sbc, with twin turbos, t3/t4 hybrids, 500 hp each turbo, made 1014 hp and 960 ft/lbs .
WHY does the hp and torque fall off after 6300 rpm. Useing OEM 882 cylinder heads, mid 7's in comp ratio, and approx mid 20's boost.
Used 2 different cams, 1- dual 237 @ .050 with 114 lobe sep, 2- 256 in@ .050 and 107 centre line 245 ex @ .050 with 121 centre line and 114 lob sep.
No hp change with cam change BUT increase with 500-600 rpm range of torque( max torque longer by 500-600rpm )
QUESTION: intake runner size control what rpm the engine makes power???
QUESTION: cam size/dur control rate of which power comeds on???
QUESTION: will more static comp, and same or less boost increase or decrease max hp, and control where it is made???
THanks for looking
ASH
turbocharged 350 sbc cylinder head design
Moderator: Team
Ok, thats not a bad idea. But there is only 2.8 liters of engine per turbo, i thought that would be ok with the t3/t4 turbonetics turbo?ROGUE GTS wrote:Need a little more info but my first guess would be the exhaust housing on the turbo is a major restriction. Have you done any pressure readings on the hot side vs cold?
HP will go up with an increase in compression/boost providing it doesn't go into detonation.
No pressures from hot side. cold only 16 to 24 psi depending on track conditions and how good the start line is...
ash
Ok, thats not a bad idea. But there is only 2.8 liters of engine per turbo, i thought that would be ok with the t3/t4 turbonetics turbo?
No pressures from hot side. cold only 16 to 24 psi depending on track conditions and how good the start line is...
ash[/quote]
Which T3 housing do you have? What A/R and diameter wheel?
My first guess would also be the exhaust housing.
No pressures from hot side. cold only 16 to 24 psi depending on track conditions and how good the start line is...
ash[/quote]
Which T3 housing do you have? What A/R and diameter wheel?
My first guess would also be the exhaust housing.
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Keith Morganstein
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Which T3 housing do you have? What A/R and diameter wheel?bobqzzi wrote:Ok, thats not a bad idea. But there is only 2.8 liters of engine per turbo, i thought that would be ok with the t3/t4 turbonetics turbo?
No pressures from hot side. cold only 16 to 24 psi depending on track conditions and how good the start line is...
ash
My first guess would also be the exhaust housing.[/quote]
stage 3 ex wheel with .82 a/r housing. Have to look up the turbonetics site for measurements.
At full load, the egts are about 1050 deg F
Using methanol
[HP will go up with an increase in compression/boost providing it doesn't go into detonation.[/quote]
What about the idea of "taking out piston volume, and replacing it with air... and therefore fuel as well to burn = more hp?
Other words.... decrease comp to allow more air/fuel to burn?
Use more boost to force fill the cylinder with less static comp.
?
Thanks Ash
What about the idea of "taking out piston volume, and replacing it with air... and therefore fuel as well to burn = more hp?
Other words.... decrease comp to allow more air/fuel to burn?
Use more boost to force fill the cylinder with less static comp.
?
Thanks Ash
.82a/r housings can often aspirate a Honda beyond 7k rpm in single turbo 500hp applications. A couple questions might get you in the right frame of mind to tackle this issue:
Are you using log/cast manifolds?
Have you characterised the torque curve at lower boost levels or waste gates stuck open boost levels?
What is your pre-intercooler temperature? Are you adequately intercooled? And how are you accomplishing this?
The results of all that dyno time could have been helped along a great deal with exhaust manifold pressure data and intake air temperature data. I hope you have some low boost runs to look at though.
Lower compression ratios keep the piston out of the way during overlap and help cylinder filling in that way alone. Swept volume is swept volume. Compression ratio is going to effect thermodynamic efficiency and EGTs more than its going to interfere with air coming out of the intake valve though. With that low CR, you are forcing yourself to make power with pressure ratios meaning more air and more fuel rather than efficiently using that mixture. High boost taxes the turbo and even at 100% intercooler efficiency, raises intake temperatures. This will all require more and more exhaust back pressure to increase turbine output. You will automatically run into exhaust choke sooner due to compressor requirements.
On top of that, these low CR can be self defeating in that they cannot effectively use the plentiful quench area of the closed chamber of a SBC wedge head. Likewise, increasing CR, you are going to make thermal gains but still no quench to improve the burn characteristics.
I will also assume that you are using leaded fuels. I think you may have gone a little conservative with CR.
You have a big hunk of old-school iron. You have given it some old school compression ratio and hanged two back pressure devices on the old-school exhaust manifolds. You are attempting to compress and ingest ~2.5 atmospheres into its interior and you should expect an uphill battle to get it to do all this past 6800 RPM.
Are you using log/cast manifolds?
Have you characterised the torque curve at lower boost levels or waste gates stuck open boost levels?
What is your pre-intercooler temperature? Are you adequately intercooled? And how are you accomplishing this?
The results of all that dyno time could have been helped along a great deal with exhaust manifold pressure data and intake air temperature data. I hope you have some low boost runs to look at though.
Lower compression ratios keep the piston out of the way during overlap and help cylinder filling in that way alone. Swept volume is swept volume. Compression ratio is going to effect thermodynamic efficiency and EGTs more than its going to interfere with air coming out of the intake valve though. With that low CR, you are forcing yourself to make power with pressure ratios meaning more air and more fuel rather than efficiently using that mixture. High boost taxes the turbo and even at 100% intercooler efficiency, raises intake temperatures. This will all require more and more exhaust back pressure to increase turbine output. You will automatically run into exhaust choke sooner due to compressor requirements.
On top of that, these low CR can be self defeating in that they cannot effectively use the plentiful quench area of the closed chamber of a SBC wedge head. Likewise, increasing CR, you are going to make thermal gains but still no quench to improve the burn characteristics.
I will also assume that you are using leaded fuels. I think you may have gone a little conservative with CR.
You have a big hunk of old-school iron. You have given it some old school compression ratio and hanged two back pressure devices on the old-school exhaust manifolds. You are attempting to compress and ingest ~2.5 atmospheres into its interior and you should expect an uphill battle to get it to do all this past 6800 RPM.
Real torque curves don't have a 2nd derivative
cencodsm wrote:.82a/r housings can often aspirate a Honda beyond 7k rpm in single turbo 500hp applications. A couple questions might get you in the right frame of mind to tackle this issue:
Are you using log/cast manifolds?
Have you characterised the torque curve at lower boost levels or waste gates stuck open boost levels?
What is your pre-intercooler temperature? Are you adequately intercooled? And how are you accomplishing this?
The results of all that dyno time could have been helped along a great deal with exhaust manifold pressure data and intake air temperature data. I hope you have some low boost runs to look at though.
Lower compression ratios keep the piston out of the way during overlap and help cylinder filling in that way alone. Swept volume is swept volume. Compression ratio is going to effect thermodynamic efficiency and EGTs more than its going to interfere with air coming out of the intake valve though. With that low CR, you are forcing yourself to make power with pressure ratios meaning more air and more fuel rather than efficiently using that mixture. High boost taxes the turbo and even at 100% intercooler efficiency, raises intake temperatures. This will all require more and more exhaust back pressure to increase turbine output. You will automatically run into exhaust choke sooner due to compressor requirements.
On top of that, these low CR can be self defeating in that they cannot effectively use the plentiful quench area of the closed chamber of a SBC wedge head. Likewise, increasing CR, you are going to make thermal gains but still no quench to improve the burn characteristics.
I will also assume that you are using leaded fuels. I think you may have gone a little conservative with CR.
You have a big hunk of old-school iron. You have given it some old school compression ratio and hanged two back pressure devices on the old-school exhaust manifolds. You are attempting to compress and ingest ~2.5 atmospheres into its interior and you should expect an uphill battle to get it to do all this past 6800 RPM.
Thanks for your reply:
-Using fab. exhaust manifolds and fab. intake manifolds
- waste gate open test results
- using methanol fuel, high spped/ blown nozzels up in the plenum, approx 125 deg C temps out the turbo, and 54 deg C into intake runner, before... the unblown nozzels.
- one thing i have to do is gain exhaust manifold pressuress
Try a couple of passes are the strip the other day, bad start line, 1.9 to 2.1 60 foot times, went 9.2 @ 170 mph.
Regards
Ash