LS9 DOHC / LS8 / And end of life for LS7
07-03-2006, 12:27 PM
#281
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Originally Posted by 300bhp/ton
Increased curtain area from multivalves will alow DOHC engine to have a broader rpm range. so in fairness it would be much closer than you think.
And also don't just be a typical or should that be stereo typical moron. You need to note that most DOHC engines (not all!!!! But most) are short stroke motors as this is better suited to high rpms which is where DOHC valve trains work well and again because HP = torque x rpm / 5252 is how to make more HP. Most OHV engines don't like revs and the valve train certainly doesn't cope with them so well so you''l find that by compariosn OHV motors are usually long stroke. And long strong motors as a trend will produce more low end torque. So don't let this OVERLOOKED aspect cloud your judgement when you make sweeping statements about under the curve.
Antoher thing to consider is gearing. If a cammed OHV looses it's low end then there is a limit to how much gear can be run or how high a gear (numerically lower).
So for the same gearing if a DOHC motor can spin 1000rpm fast it will also allow higher top speeds.
Only in America.
Go and look at the rest of the world.
A V8 works no differently to a V6 or in basic terms even an in line 4 cylinder engine. Yet how many V6's and S4's the world over are OHV and which valve train configuration produces the most power?
Do you see Formula 1 engines being OHV? No, because they just wouldn't make the power.
Yes OHV works very well on the street and due to the American automakers there are plenty of cheap mass produced OHV V8's of large displacement.
But again don't let the lack of mass produced LARGE displacement DOHC engines cloud your technical judgement.
For any given displacement on a like for like basis a DOHC will out perform a OHV V8 and with only a slight penalty in size and weight. Bore spacing and deck hieght have no relavance because the shape and design of each engine is specific to it's own layout. With a DOHC engine the block can be smaller due to no need for a cam or pushrods within it. The heads evidently need to be larger to accomodate the cams, but probably not that much larger as a OHV engine heads still have to house the rocker arms anyhow.
And another ORVERLOOKED fact is many DOHC engines have a different angle Vee (45 compared to 90) due to the fact of not needing to house the cam and push rods. This means they will be a different shape, either taller or wider but often not both.
Are you serisously trying to make this personal???
please grow up for pitys sake!
And also don't just be a typical or should that be stereo typical moron. You need to note that most DOHC engines (not all!!!! But most) are short stroke motors as this is better suited to high rpms which is where DOHC valve trains work well and again because HP = torque x rpm / 5252 is how to make more HP. Most OHV engines don't like revs and the valve train certainly doesn't cope with them so well so you''l find that by compariosn OHV motors are usually long stroke. And long strong motors as a trend will produce more low end torque. So don't let this OVERLOOKED aspect cloud your judgement when you make sweeping statements about under the curve.
Antoher thing to consider is gearing. If a cammed OHV looses it's low end then there is a limit to how much gear can be run or how high a gear (numerically lower).
So for the same gearing if a DOHC motor can spin 1000rpm fast it will also allow higher top speeds.
Only in America.
Go and look at the rest of the world.
A V8 works no differently to a V6 or in basic terms even an in line 4 cylinder engine. Yet how many V6's and S4's the world over are OHV and which valve train configuration produces the most power?
Do you see Formula 1 engines being OHV? No, because they just wouldn't make the power.
Yes OHV works very well on the street and due to the American automakers there are plenty of cheap mass produced OHV V8's of large displacement.
But again don't let the lack of mass produced LARGE displacement DOHC engines cloud your technical judgement.
For any given displacement on a like for like basis a DOHC will out perform a OHV V8 and with only a slight penalty in size and weight. Bore spacing and deck hieght have no relavance because the shape and design of each engine is specific to it's own layout. With a DOHC engine the block can be smaller due to no need for a cam or pushrods within it. The heads evidently need to be larger to accomodate the cams, but probably not that much larger as a OHV engine heads still have to house the rocker arms anyhow.
And another ORVERLOOKED fact is many DOHC engines have a different angle Vee (45 compared to 90) due to the fact of not needing to house the cam and push rods. This means they will be a different shape, either taller or wider but often not both.
Are you serisously trying to make this personal???
please grow up for pitys sake!
.So you say the dohc will produce more power than an ohv motor, i don't think anybody here would argue that, of course there are always exceptions. However again lets step from your fantasy supercar f1 world back into reality. On a full production car the dohc motor is going to cost a lot more. You're going to be able to build a larger displacement ohv motor that's still smaller and makes the same power for a lot cheaper, that means the car goes to the consumer for cheaper which mean more cars sell. Also you can run a ohc motor at a more shallow angle, you need to if engine compartment space is tight like in modern cars. Guess what though, that just raises the cog of the motor and the car which hurts handling.
Last edited by stik6shift93; 07-03-2006 at 12:41 PM.
07-03-2006, 12:28 PM
#282
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Originally Posted by 300bhp/ton
Ok then.
How much HP does a stock displacement LS1 (5.7 litre or 346ci) produce on 93 octane street tune running a supercharger (preferably a twin screw for comparisons sake).
I guess to be fair you really need to find one running ~ 8.5:1 SCR.
There are many examples of Terminators making 620-650rwhp (admittidly I think on dynojets) with a 2.2 twin screw blower and bolt ons STOCK internals and on 93 octane fuel.
Only about 10 days back there was a turbo 5.7 LS1 running 9.1:1 SCR and 15lb of boost in the FI forum, I believe they where making high 500's although with a better exhaust it should have been high 600's. But isn't it amazing how close the DOHC 4.6 gets to the 5.7 LS1 considering it is giving away 1.1 litres.
If I'm wrong please go and find some dyno graphs of stock displacement blown LS1's.
How much HP does a stock displacement LS1 (5.7 litre or 346ci) produce on 93 octane street tune running a supercharger (preferably a twin screw for comparisons sake).
I guess to be fair you really need to find one running ~ 8.5:1 SCR.
There are many examples of Terminators making 620-650rwhp (admittidly I think on dynojets) with a 2.2 twin screw blower and bolt ons STOCK internals and on 93 octane fuel.
Only about 10 days back there was a turbo 5.7 LS1 running 9.1:1 SCR and 15lb of boost in the FI forum, I believe they where making high 500's although with a better exhaust it should have been high 600's. But isn't it amazing how close the DOHC 4.6 gets to the 5.7 LS1 considering it is giving away 1.1 litres.
If I'm wrong please go and find some dyno graphs of stock displacement blown LS1's.
How about some of the SBC guys running big turbos at 25-30psi making over 1500hp? That is pretty amazing. There was a thread on here somewhere of GM's up and coming blown 6.2L LS9 recently. Made 650hp. Its amazing what is possible with FI when the engine is built for it straight from the factory.
07-03-2006, 12:39 PM
#283
Wow if a 5.7 liter ls1 is making only 500+ rwhp with 15 POUNDS OF BOOST, then something is significantly wrong...A stock ls1 with 8 psi can make that amount with bolt ons so how can a 15 psi 5.7 liter ls1 only make 500+ rwhp? That makes ZERO sense, no matter how restictive the exhaust is....
07-03-2006, 12:40 PM
#284
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Originally Posted by 300bhp/ton
Ok then.
How much HP does a stock displacement LS1 (5.7 litre or 346ci) produce on 93 octane street tune running a supercharger (preferably a twin screw for comparisons sake).
I guess to be fair you really need to find one running ~ 8.5:1 SCR.
There are many examples of Terminators making 620-650rwhp (admittidly I think on dynojets) with a 2.2 twin screw blower and bolt ons STOCK internals and on 93 octane fuel.
Only about 10 days back there was a turbo 5.7 LS1 running 9.1:1 SCR and 15lb of boost in the FI forum, I believe they where making high 500's although with a better exhaust it should have been high 600's. But isn't it amazing how close the DOHC 4.6 gets to the 5.7 LS1 considering it is giving away 1.1 litres.
If I'm wrong please go and find some dyno graphs of stock displacement blown LS1's.
How much HP does a stock displacement LS1 (5.7 litre or 346ci) produce on 93 octane street tune running a supercharger (preferably a twin screw for comparisons sake).
I guess to be fair you really need to find one running ~ 8.5:1 SCR.
There are many examples of Terminators making 620-650rwhp (admittidly I think on dynojets) with a 2.2 twin screw blower and bolt ons STOCK internals and on 93 octane fuel.
Only about 10 days back there was a turbo 5.7 LS1 running 9.1:1 SCR and 15lb of boost in the FI forum, I believe they where making high 500's although with a better exhaust it should have been high 600's. But isn't it amazing how close the DOHC 4.6 gets to the 5.7 LS1 considering it is giving away 1.1 litres.
If I'm wrong please go and find some dyno graphs of stock displacement blown LS1's.
07-03-2006, 05:43 PM
#285
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I have a question regarding 4V DOHC vs pushrod motors that may sound stupid but here goes:
Wouldn't a 4V DOHC motor tend to have better head flow velocity then a 2V pushrod motor with the same bore, stroke, and head runner size? With the 4V motor having smaller valves it seems to me that they would have better velocity and thus better low end and midrange then the 2V pushrod. However, the 4V Cobras (N/A models) and Mach1's are peakier then the PI 2V 4.6 GT's. Unless the cams and head runners in the 4V motors are significantly bigger, what is the reason for the 4V's being peakier then the 2V's? After all, the valves in the 4V's are smaller then the 2V's right?
Jason
Wouldn't a 4V DOHC motor tend to have better head flow velocity then a 2V pushrod motor with the same bore, stroke, and head runner size? With the 4V motor having smaller valves it seems to me that they would have better velocity and thus better low end and midrange then the 2V pushrod. However, the 4V Cobras (N/A models) and Mach1's are peakier then the PI 2V 4.6 GT's. Unless the cams and head runners in the 4V motors are significantly bigger, what is the reason for the 4V's being peakier then the 2V's? After all, the valves in the 4V's are smaller then the 2V's right?
Jason
07-03-2006, 06:03 PM
#286
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Actually a 4 valve motor is going to have a larger combined port volume than a comparable two valve motor. Each valve will have less port volume however you have to think of them as a combined unit. This creates a problem with keeping up port velocity at low rpms and will give it worse low end torque, to combate this most manufacturers run a longer stroke than you would on a comparable two valve production motor.
07-04-2006, 08:46 PM
#287
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4v heads flow insane in comparison to 2 valves, this alone helps with top end hp. I guess there is no real thing i can say that can prove my throries, thats all i was doin was sharing an opinion and a theory with u guys lol. Everyone bashed on me pretty hard, dont get me wrong ima chevy guy just like all of u. Anyways, maybe someone else can come off what ive said and get something out of it. Otherwise i still think a pushrod GM platform is the best dollar for dollar motor (LS1 LS2 LS7 even LT1) that u can buy out there.
07-04-2006, 10:37 PM
#288
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didn't read the whole thread, but here's my .02
anything can be made fast if you put enough money into it (hell there were some fr wheel drive civics and scions running 8s on Speed a while ago), but the great thing about fbodies and vettes is they can run 10s or 11s one day, and the next tear up a road course, and in between get 20+ mpg. IMO they are the most affordable, reliable, and are the easiest to maintain and modify. that's why i don't have a supra or stang, and probably never will. that said, an ohc motor has more potential than a pushrod motor, just look at formula 1... wow.
Edit: the exception is definately NHRA top fuel
anything can be made fast if you put enough money into it (hell there were some fr wheel drive civics and scions running 8s on Speed a while ago), but the great thing about fbodies and vettes is they can run 10s or 11s one day, and the next tear up a road course, and in between get 20+ mpg. IMO they are the most affordable, reliable, and are the easiest to maintain and modify. that's why i don't have a supra or stang, and probably never will. that said, an ohc motor has more potential than a pushrod motor, just look at formula 1... wow.
Edit: the exception is definately NHRA top fuel
Last edited by chevynation; 07-04-2006 at 10:44 PM.
07-04-2006, 11:13 PM
#289
Originally Posted by chevynation
that said, an ohc motor has more potential than a pushrod motor, just look at formula 1... wow.
It's the kind of thinking that doesn't see the forest for the trees. The same mentality that spawns ricer math.
07-05-2006, 07:33 PM
#290
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Informative article below on 2 vs 4 valve head design. Basically says for a given total valve area, 2 smaller valves flow better than 1 single valve at low lifts because the 2 smaller valves have a greater total diameter
http://www.pumaracing.co.uk/pp02.htm
http://www.pumaracing.co.uk/pp02.htm
07-06-2006, 10:17 PM
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Originally Posted by 93LT1
4v heads flow insane in comparison to 2 valves, this alone helps with top end hp. I guess there is no real thing i can say that can prove my throries, thats all i was doin was sharing an opinion and a theory with u guys lol. Everyone bashed on me pretty hard, dont get me wrong ima chevy guy just like all of u. Anyways, maybe someone else can come off what ive said and get something out of it. Otherwise i still think a pushrod GM platform is the best dollar for dollar motor (LS1 LS2 LS7 even LT1) that u can buy out there.
07-06-2006, 10:24 PM
#293
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Originally Posted by UMD_Jesse
Informative article below on 2 vs 4 valve head design. Basically says for a given total valve area, 2 smaller valves flow better than 1 single valve at low lifts because the 2 smaller valves have a greater total diameter
http://www.pumaracing.co.uk/pp02.htm
http://www.pumaracing.co.uk/pp02.htm
07-07-2006, 11:46 AM
#294
Originally Posted by stik6shift93
Actually i believe lingenfelter makes a 415ci setup for them.
The LT5s also received the 3.45 gears and Zf gearing same as the LT1. They do wake up with a set of gears.
Yes they have swapped LT5s into other cars but it is a rather expensive project, most were done for the wow factor. If you search Nine Ball's YearOne pics there is a LT5 TT in a 67 Chevelle.
Last edited by 93Polo; 07-11-2006 at 10:33 AM.
07-07-2006, 11:54 AM
#295
Originally Posted by black_knight
Comparing limited production engines? Try the LS7. Oh, but you want to up the displacement on the LT5 to compete?
What's that? You can't?
Yeah, that's why OHV wins. You can run more displacement.
What's that? You can't?
Yeah, that's why OHV wins. You can run more displacement.
07-08-2006, 01:33 AM
#296
Originally Posted by 93Polo
07-11-2006, 10:32 AM
#297
Originally Posted by black_knight
'I stand corrected. My point, however, remains valid. (think the warlock) Are you disputing that OHV can run more cubes for a given external engine size/weight?
However, there are many misconceptions about how much a LT5 can be modified and how they perform.
07-13-2006, 07:16 AM
#298
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Originally Posted by DrkPhx
Look at the date of the thread; 10-20-05. Seems like this guy is "in the know" pretty good with someone at GM. Just from a business standpoint, it doesn't make sense for GM to simply discontinue the LS7 after spending so much on R&D, tooling and production costs. My guess is it will show up in other GM performance vehicles (no dry sump) to recoup some of the high costs of the engine. In fact it's probably a given it will, especially if they drop it from the Corvette line.
Do you think the LS7 could make it into the base model C6 by 2011?
07-14-2006, 07:18 AM
#300
Originally Posted by 02SOMWS6
Heres the best part, the single overdead cam set up in the LS7 is going to be considered out dated. That means prices will drop on LS7 stuff. I don't know about you guys but I don't need to be that high tech and will love to see the prices drop.