Twins vs. Single on a V8
TECH Fanatic
Joined: Mar 2002
Posts: 1,044
Likes: 0
Re: Twins vs. Single on a V8 </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Pro Stock John:
<strong>I wonder what size downpipe and downstream piping we would need to run to support a T76 or a T88.... 4" down pipe?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Rob of LS1M ran a 3" downpipe for his 9 sec run.
Below is from his web page:
"375c.i. iron block Agostino Racing built LS1 engine. Stock crank, Lunati Pro-Billet Rods, Ross custom "turbo" 8.5:1 forged pistons, custom main studs, ARP Head studs, O-ringed block, Ported & polished heads, 558lift hydraulic roller camshaft, stock lifters, LS6 intake, ported stock throttle body, SLP 85mm MAF, MSD 50# injectors, custom built single turbo kit, T-74 turbo, Spearco Front-mount intercooler, 3" downpipe, 4" Mufflex exhaust w/Borla XR1 4" muffler, complete custom-built fuel system using an Aeromotive 1800Hp external pump, -10 feed line, -6 return line, Aeromotive 1:1 boost sensitive regulator, modified stock fuel rail"
<small>[ December 21, 2002, 10:58 AM: Message edited by: SS00Blue ]</small>
<strong>I wonder what size downpipe and downstream piping we would need to run to support a T76 or a T88.... 4" down pipe?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Rob of LS1M ran a 3" downpipe for his 9 sec run.
Below is from his web page:
"375c.i. iron block Agostino Racing built LS1 engine. Stock crank, Lunati Pro-Billet Rods, Ross custom "turbo" 8.5:1 forged pistons, custom main studs, ARP Head studs, O-ringed block, Ported & polished heads, 558lift hydraulic roller camshaft, stock lifters, LS6 intake, ported stock throttle body, SLP 85mm MAF, MSD 50# injectors, custom built single turbo kit, T-74 turbo, Spearco Front-mount intercooler, 3" downpipe, 4" Mufflex exhaust w/Borla XR1 4" muffler, complete custom-built fuel system using an Aeromotive 1800Hp external pump, -10 feed line, -6 return line, Aeromotive 1:1 boost sensitive regulator, modified stock fuel rail"
<small>[ December 21, 2002, 10:58 AM: Message edited by: SS00Blue ]</small>
Re: Twins vs. Single on a V8 [/QUOTE]However in kits such as Rob's kit which combines a quality turbo and well designed plumbing(turbo is also close to the engine)... spool up times between it and a comparable twin set-up are negligible.... so you get the best of both worlds.... quick boost as well as enough of a hairdryer for big power up top.[/QB][/QUOTE]
I'm a bit confused on the "turbo is also close to the engine" point.
What's this long pipe that runs from the passenger side then? I'm not saying it'll make a difference but a long crossover pipe changed a few things.
<img src="http://www.ls1motorsports.com/images/TurboExAndCross.jpg" alt=" - " />
Versus a twin which looks like this on both sides.
<img src="http://www.ls1turbo.com/images/turbosystemside2.jpg" alt=" - " />
Any concerns on tuning from one bank to the next? I have EGT's after each turbo which can tell me if one bank is acting up versus another. What about heat around the motor. Or heat loss and thus pulse energy loss. Ahh it's probably all pretty close. Anyway...carry on...good discussion.
I'm a bit confused on the "turbo is also close to the engine" point.
What's this long pipe that runs from the passenger side then? I'm not saying it'll make a difference but a long crossover pipe changed a few things.
<img src="http://www.ls1motorsports.com/images/TurboExAndCross.jpg" alt=" - " />
Versus a twin which looks like this on both sides.
<img src="http://www.ls1turbo.com/images/turbosystemside2.jpg" alt=" - " />
Any concerns on tuning from one bank to the next? I have EGT's after each turbo which can tell me if one bank is acting up versus another. What about heat around the motor. Or heat loss and thus pulse energy loss. Ahh it's probably all pretty close. Anyway...carry on...good discussion.
Re: Twins vs. Single on a V8 </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">a properly configured and sized single turbo will always overpower a twin turbo.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i agree... it's kinda like how a 5" ID pipe will flow more than (2) 2.5" ID pipes.
Theoretically two smaller turbos have a lower total inertia to overcome..and if the rest of both systems are equal in efficiency... the twins will spool quicker..but be limited in topend power due to flow issues.
However in kits such as Rob's kit which combines a quality turbo and well designed plumbing(turbo is also close to the engine)... spool up times between it and a comparable twin set-up are negligible.... so you get the best of both worlds.... quick boost as well as enough of a hairdryer for big power up top.
that is all... <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
Theoretically two smaller turbos have a lower total inertia to overcome..and if the rest of both systems are equal in efficiency... the twins will spool quicker..but be limited in topend power due to flow issues.
However in kits such as Rob's kit which combines a quality turbo and well designed plumbing(turbo is also close to the engine)... spool up times between it and a comparable twin set-up are negligible.... so you get the best of both worlds.... quick boost as well as enough of a hairdryer for big power up top.
that is all... <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
Re: Twins vs. Single on a V8 </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">I'm a bit confused on the "turbo is also close to the engine" point.
What's this long pipe that runs from the passenger side then? I'm not saying it'll make a difference but a long crossover pipe changed a few things.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">sorry... that ended up sounding a little different than i intended.. i meant "good plumbing" as in on the passenger side, Rob's kit uses the stock manifold, which is thick cast iron, so it helps to hold the heat in, the rest of the tubing is fairly thick SS and from what i understand, he has moved the turbo up slightly compared to the Turbo tech kit (as well as $$better$$ tubing material)... and from the insane torque numbers he is getting with the kit, i'd say the boost is there in full, very early.
What's this long pipe that runs from the passenger side then? I'm not saying it'll make a difference but a long crossover pipe changed a few things.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">sorry... that ended up sounding a little different than i intended.. i meant "good plumbing" as in on the passenger side, Rob's kit uses the stock manifold, which is thick cast iron, so it helps to hold the heat in, the rest of the tubing is fairly thick SS and from what i understand, he has moved the turbo up slightly compared to the Turbo tech kit (as well as $$better$$ tubing material)... and from the insane torque numbers he is getting with the kit, i'd say the boost is there in full, very early.
Re: Twins vs. Single on a V8 First of all I just want to say that I am not against a single turbo setup. Also let me say that I am not trying to pick on LS1 Motorsports Kit. I let their HP and TQ numbers speak for themselves. However in the design of the Twin Turbo kit I ran up against discussions about header design and turbo performance that were for the most part went into improving the kit design. Given that here are some flaws that you should look into while considering either making or buying a kit.
Turbos should be close (within reason) to the exhaust pulses. A single turbo kit with a crossover tube will lose heat and thus energy prior to it pulsing the turbo.
Rice Etr, I'm not sure what tube quality would retain heat? Do you happen to know thickness and alloy? Or is the production piece ceramic coated? I just don't see how it'll retain the heat. I'm familiar with most alloys so don't be afraid to throw it at me.
Also another thing to be concerned about is where exhaust pulses (due to piping angle) are being bounced into each other or being bounced into a sharp angle (as in bouncing it directly into a log). These cause all kinds of negatives towards allowing free flowing pulses. Otherwise what you have is reversion and a lack of scavanging. The crossover tube is one that you REALLY need to focus on since it has 4 pulses coming out of it. As I look at the direction of the crossover tube within the LS1M kit it really should have a better angle from what I can see.
Turbos should be close (within reason) to the exhaust pulses. A single turbo kit with a crossover tube will lose heat and thus energy prior to it pulsing the turbo.
Rice Etr, I'm not sure what tube quality would retain heat? Do you happen to know thickness and alloy? Or is the production piece ceramic coated? I just don't see how it'll retain the heat. I'm familiar with most alloys so don't be afraid to throw it at me.
Also another thing to be concerned about is where exhaust pulses (due to piping angle) are being bounced into each other or being bounced into a sharp angle (as in bouncing it directly into a log). These cause all kinds of negatives towards allowing free flowing pulses. Otherwise what you have is reversion and a lack of scavanging. The crossover tube is one that you REALLY need to focus on since it has 4 pulses coming out of it. As I look at the direction of the crossover tube within the LS1M kit it really should have a better angle from what I can see.
TECH Fanatic
Joined: Nov 2001
Posts: 1,055
Likes: 0
From: Chi-Town
Re: Twins vs. Single on a V8 One thing that i have noticed in the few years i have been dealing with turbo cars and from the experience with a few friends that i have is that on a street car, even a street/strip car an extremely efficient header setup is not needed. A decent log setup will work well as long as the backpressure isn't very high. There are various setups all over the place in different configurations via ford, chevy, import that do not have headers and work very very well.
just my .02
just my .02
