What if you designed a striaght 8 LSX???
Thread Starter
TECH Regular
Joined: Feb 2008
Posts: 458
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From: Keller, Texas
What if you designed a striaght 8 LSX??? After reading about the straight 8 engine, the design died off was because of the the physical length. Manufactures couldn't fit a straight 8 into a modern cars. They were used in luxury and sports cars for 50 years. Lets say GM ditched the V8 design and adapted the straight 8 design for the LS Series. The main benefit of a straight engine is the limited torsional vibration. That means better bearing wear and less friction. Straight engines run very smooth and have a smooth acceleration.
Would a straight 8 LS Series engine outperform a V8 LS Series engine?
Also don't argue about disadvantage of length and weight.
Would a straight 8 LS Series engine outperform a V8 LS Series engine?
Also don't argue about disadvantage of length and weight.
TECH Junkie
Joined: Dec 2005
Posts: 3,092
Likes: 11
Sure, it could be done quite easily. However because of the packaging it won't be. You could lay it over a little and that would create some interesting intake and exhaust situations that you cannot do with a V8. One thing would be exhaust pipe pairing.
Last edited by 1989GTA; Feb 21, 2011 at 09:18 PM.
where did you read about straight 8's ?
wiki has a lot of decent info on inlines from I-4 on up, the info under the I-5 is probably the most revealing.
would a straight 8 outperform a v-8 disregarding weight and packaging, I think so based on having a common exhaust manifold for all 8 cylinders so you can take more advantage of exhaust tuning. You also get even firing pulses per revolution opposed to uneven firing pulses of a 90 deg V-8.
I don't think a straight 8 would have less torsional vibration than a v-8, it would have more because the crank is twice as long. A straight 8 however is more balanced than a 90 deg V-8 in regards to 1st and 2nd order harmonics since the crank throws balance each other out. Whether the crank length and vibration would matter I don't know, the 90-deg V-8 has heavy crank counterweights, and an inline-4 which is probably more common has 2nd order imbalance and both can go many miles/hours so I don't think it's that big a deal regarding durability.
the thing is though, if you're thinking about changing the common 90-deg (cross plane crank) v-8 design for something better, yes an inline-8 is one way to go.
But there is the single plane crank v-8 that's used in race motors where the crank throws resemble that of an inline-4 crank, so it has 2nd order balance problems but the evenly spaced firing pulses allows for better exhaust tuning and it doesn't need crank counterweights so it has less crank mass and can accelerate faster, hence the use of it in race motors I suppose would mean it performs better than the crossplane v-8 crank so why not go with a single plane crank?
In regards to going to an inline-8 over a v-8, consider a v-12 is inherently balanced on 1st and 2nd order, it has 4 more cylinders over an 8 cylinder hence better output, and is 2 cylinders shortly than an inline-8.
wiki has a lot of decent info on inlines from I-4 on up, the info under the I-5 is probably the most revealing.
would a straight 8 outperform a v-8 disregarding weight and packaging, I think so based on having a common exhaust manifold for all 8 cylinders so you can take more advantage of exhaust tuning. You also get even firing pulses per revolution opposed to uneven firing pulses of a 90 deg V-8.
I don't think a straight 8 would have less torsional vibration than a v-8, it would have more because the crank is twice as long. A straight 8 however is more balanced than a 90 deg V-8 in regards to 1st and 2nd order harmonics since the crank throws balance each other out. Whether the crank length and vibration would matter I don't know, the 90-deg V-8 has heavy crank counterweights, and an inline-4 which is probably more common has 2nd order imbalance and both can go many miles/hours so I don't think it's that big a deal regarding durability.
the thing is though, if you're thinking about changing the common 90-deg (cross plane crank) v-8 design for something better, yes an inline-8 is one way to go.
But there is the single plane crank v-8 that's used in race motors where the crank throws resemble that of an inline-4 crank, so it has 2nd order balance problems but the evenly spaced firing pulses allows for better exhaust tuning and it doesn't need crank counterweights so it has less crank mass and can accelerate faster, hence the use of it in race motors I suppose would mean it performs better than the crossplane v-8 crank so why not go with a single plane crank?
In regards to going to an inline-8 over a v-8, consider a v-12 is inherently balanced on 1st and 2nd order, it has 4 more cylinders over an 8 cylinder hence better output, and is 2 cylinders shortly than an inline-8.
Teching In
Joined: Feb 2009
Posts: 33
Likes: 0
From: Va Beach
They kind of explored this idea a few years ago with the LL8 4200 Vortec Inline 6. Made 291hp 275ft-lbs. I would imagine an 8 would make quite a bit more torque very low in the rpm range.
There were some people who modified them...
There were some people who modified them...
12 Second Club
Joined: Dec 2008
Posts: 281
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From: A small town, MS
An inline 8 would certainly make more torque, but I would think that the horsepower would suffer do to the inline cylinders being less energy efficient, as with an inline six. However, a V10 or V12 LSX motor would be incredible.
Or even a W configuration. I believe that its BMW that makes a W12 configuration motor. It has a near flatline torque curve
Or even a W configuration. I believe that its BMW that makes a W12 configuration motor. It has a near flatline torque curve
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As for an I8, that would be interesting. Maybe for a coupe/truck with a long nose it would fit?
TECH Regular
Joined: Jan 2005
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From: Orlaanndoooo
Wow, all the trouble of twin turbos and all they were able to get was 37% more power? I know it's not intercooled which hurts the big numbers but damn.
You're quoting the stock HP/TQ numbers for 06-07 I6s, the turbo one you pictured makes 400/400 hp/tq and was only ever installed in 1 02 TrailBlazer. Dang shame GM never let anyone with EFILive/HPTuners read the PCM, we're screwed when trying to tune for boost.
As for an I8, that would be interesting. Maybe for a coupe/truck with a long nose it would fit?
As for an I8, that would be interesting. Maybe for a coupe/truck with a long nose it would fit?
