Why do Vipers have such small valves and headers?

[Mopar]

Can anyone answer this for me because I do not understand why this is. The 488ci has the the SAME valve size and a Small Block Chevy(1.94) and well as the header size(1 3/4). Only thing I can think of is that they designed these motors to very street friendly and have monster abount of torque at low rpms thus for the small valves and headers.

Can anyone enlighten me??

 

[Ron Weickart]

The Viper V-10 is basically a small block V-8 with an extra set of pistons added to make it a V-10. That is, cylinder for cylinder, the swept volume displacement of any given cylinder on the V-10 would be similar to the swept volume displacement of any given cylinder on a small block V-8. Hence the valves and header sizes are more in line with those found on performance small blocks rather than those associated with larger piston big block V-8s.

When you drive the Viper the torque/power from the big displacemet reminds one of a real big big-block V-8, but the way it revs reminds one of a small block.

 

[onerareviper]

When you drive the Viper the torque/power from the big displacemet reminds one of a real big big-block V-8, but the way it revs reminds one of a small block.

Great description! I always loved the torque of a big block V8, but liked the way a built 302 or 350 revved. The V10 seems to give the best of both worlds, especially with aftermarket headers/exhaust.

BTW - A stock Viper does not have 1 3/4 headers. That's aftermarket. Stock is 1 1/2 - If memory serves. Maybe less. Someone verify....

 

[FE 065]

It's a 390V8 with 2 added cylinders.

 

[Torquemonster]

As above - 2 words - 10 cylinders - not 8.

Bigger is not always better - sometimes it's just more

Big 2" primaries like a 500 cube V8 could take would lose considerable power under the curve. Big 2.25" intakes just won't fit right on a small 4" bore and would be silly at stock rpm limits.... can you say "pig" - that's what you'd have.

 

[Mopar]

Bigger is not always better - sometimes it's just more

Big 2" primaries like a 500 cube V8 could take would lose considerable power under the curve. Big 2.25" intakes just won't fit right on a small 4" bore and would be silly at stock rpm limits.... can you say "pig" - that's what you'd have.

I agree to an extent, just check my sig, I'm no stranger to Big Blocks. My Vette's headers has 2in primaries and 4in collectors. I'm running stock ported heads w/ 2.19/1.90 valves, and believe me I don't have any noticable loss of power under the curve. Sure, I may have loss torque, who cares w/ Big Blocks they're are plenty to sacrifice, thus I tend to build for horsepower. My first and second gears are useless unless I'm running slicks, I could only image if I had smaller valves and smaller headers.

I agree sometimes more is not better, but that is also similar to saying one has too much horsepower, it depends on whom you ask.

 

[joe117]

"believe me I don't have any noticable loss of power under the curve."

Yes you do.
You might have all the power you want but when you open up the ports and valves the way you say you did, you are going to gain some here and lose some there.

If you have a race car and the rpm never gets below 3500, you don't need to worry about low end torque.
Big ports,valves and cam don't just give you something for nothing.

Some guys port and cam their engine for a 7500 rpm power band and then drive around on the street. They never see the high rpm that they tuned for.

Did you ever dyno your Vette?

 

[GR8_ASP]

Bigger is not always better - sometimes it's just more

Big 2" primaries like a 500 cube V8 could take would lose considerable power under the curve. Big 2.25" intakes just won't fit right on a small 4" bore and would be silly at stock rpm limits.... can you say "pig" - that's what you'd have.

Mopar, I believe you misunderstood the above quote. What he is saying is that what works on a 500 ci big block may not work on the Viper as it really is essentially a 10 cylinder small block, albeit a big small block. The Vipers smaller cylinder diameter will not support the same size valves as a big block and the per cylinder flow is less, thus smaller primaries end up working better. It really isn't a cubic inch question, but how many cubic inches per cylinder. The Viper has 48.8 (Gen I & II) where a 427 has 53.4, a 454 has 56.8 and a 500 ci has 62.5. Thus in a per cylinder comparison the Viper is lower than the big blocks and on the high end of the small block scale.

 

[Craig 201 MPH]

the V-10 is just a 360 with 2 cylinders added on.

 

[GR8_ASP]

Craig, it comes out to a 390 with 2 added cylinders for the Gen I/II or 404 for the SRT. You may be correct regarding bore centers and other block geometry, but not displacement.

 

[Mopar]

Bigger is not always better - sometimes it's just more

Big 2" primaries like a 500 cube V8 could take would lose considerable power under the curve. Big 2.25" intakes just won't fit right on a small 4" bore and would be silly at stock rpm limits.... can you say "pig" - that's what you'd have.

Mopar, I believe you misunderstood the above quote. What he is saying is that what works on a 500 ci big block may not work on the Viper as it really is essentially a 10 cylinder small block, albeit a big small block. The Vipers smaller cylinder diameter will not support the same size valves as a big block and the per cylinder flow is less, thus smaller primaries end up working better. It really isn't a cubic inch question, but how many cubic inches per cylinder. The Viper has 48.8 (Gen I & II) where a 427 has 53.4, a 454 has 56.8 and a 500 ci has 62.5. Thus in a per cylinder comparison the Viper is lower than the big blocks and on the high end of the small block scale.

Ron, you were right, I did misread. I understand what you guys are saying now, it makes since when you think of it a a "Big" small block.

 

[Mopar]

[quoteDid you ever dyno your Vette?

[/QUOTE]

Joe, only an engine dyno. I'm still putting her back together and then will have it chassis dynoed.

My peak #'s came in at:

647hp @ 6,500rpms
586tq @ 5,000rpms

I plan to mount a blue bottle this Summer.

 

[CajunViper]

I thought I read that the engineers took an existing 6cyl. and a 4cyl block and made a 10. I don't remember them saying anything about the valve size. So you could say a 6cyl. with 4cyl. added or a 4cyl. with 6cyl. added. It was something the engineers have always wanted to do and Dodge let them. So really it was a brand new engine not a 360 with 2cyl. added or anything else.

Dean

 

[FE 065]

The 390ci V8 + 2 cylinders is just a reference point to compare the Viper's 48.8ci/per cylinder to other mildy tuned V8 engines of similar (390ci) displacement.

 

[Fast Freddy]

the vipers intake valve of 1.94 inches is considerably smaller than the stock intake valve size of 2.00 inches on my LS6 engine in my stock Z06 vette