Vipers and higher RPM

[Nine Ball]

The rod/stroke ratio of a SB chevy is also far more conducive to higher reving than the viper motor.

Again, as already stated:

LS7 = 4.00" stroke and 4.125" bore - 7,000 rpm redline
SRT = 3.96" stroke and 4.03" bore - 6,000 rpm redline

The SRT-10 engine has a shorter stroke, and lighter/smaller piston. The bottom end should be able to rev higher than an LS7, based on bore/stroke ratio. I understand the heads do not flow as well as an LS7, but that doesn't mean so much when you are using forced induction.

FYI, the LS3 engine has a 6500 rpm rev limit, and also uses powdered metal rods. We have been spinning stock LS1 powdered metal rods to 6800 rpm since 1999. The titanium rods in the LS7 are nice, but not required for this rpm level. Start getting into the 7500-8000 range, and they will be beneficial.

I'm assuming the Viper oiling system and crankshaft weight/harmonics are just not suitable for higher rpm. It surely isn't the bore/stroke size, those would work just fine.

 

[aries]

Tell ya what Nine Ball, do this. Remove the rev limiter and spin the crap out of your viper motor. Then when it gernades, see what broke first and that's the weak point. Then rebuild it, address the problems and you're good.

 

[Nine Ball]

Aries, you are a genius. Hopefully someone has already had the heartache and can share some experience, however. Surely some members here can have a highly technical engine design discussion?

 

[Malu59RT]

Aries, you are a genius. Hopefully someone has already had the heartache and can share some experience, however. Surely some members here can have a highly technical engine design discussion?

Tony, have you talked to ART or UGR? I'm sure they have seen it in the past and can tell you for fact, instead of us speculating.

 

[Nine Ball]

Malu, are you saying that members here have no clue and can't have a discussion based on their own experience? If so, that is somewhat sad. I suppose I can pick up the phone and bother a shop with my questions, without intending to purchase something. But then, why does a message board exist? Don't some of those shops frequent this site, maybe they can respond during their free time, instead of me bugging them on company time?

This is a "discussion" board. I'm looking to discuss the subject, hopefully with someone that may have some first hand knowledge. I'm not wanting to tie up vendors on the phone, they probably wouldn't appreciate that.

 

[JaronsToy]

Tony If this was Ls1tech.com and we were talking about the Ls7 we would have everyone telling you why it would work and why it will not, but I don't think people on here know what was done to the car when at the shop. (Not everyone but most do not know)

 

[Malu59RT]

Malu, are you saying that members here have no clue and can't have a discussion based on their own experience? If so, that is somewhat sad. I suppose I can pick up the phone and bother a shop with my questions, without intending to purchase something. But then, why does a message board exist? Don't some of those shops frequent this site, maybe they can respond during their free time, instead of me bugging them on company time?

This is a "discussion" board. I'm looking to discuss the subject, hopefully with someone that may have some first hand knowledge. I'm not wanting to tie up vendors on the phone, they probably wouldn't appreciate that.

Tony, don't know if you misunderstood my post. I didn't know if you were looking for an actual answer, based on experience, or speculation from us. A sole member might have information on his particular failure, whereas a shop would have information on multiple failures. Plus, most vendor's (UGR, Heffner, Hennessey) are trying to find the limits of these motors, not Joe Blow in his garage changing an air filter to a K&N.

If you really want to know, I'm sure most shop's wouldn't mind answering a question that would take a couple of minutes to answer (via the phone). I don't see how Mark Jorgensen coming here and spending a total of 1 hour posting back in forth via forum conversation is going to be more cost-effective than you calling him up and talking to him. That's just me.

I may have mistaken your post as looking for solid information, when you were merely looking for "discussion". Sorry

 

[Grant]

I'm assuming the Viper oiling system and crankshaft weight/harmonics are just not suitable for higher rpm. It surely isn't the bore/stroke size, those would work just fine.

Well, the only significant, RPM-limiting difference between the gen 4s and gen 3s is the oiling system, right? So Everything else is probably good to 6500 (what the gen 4 Mopar ECU revs to). It seems pretty unlikely to me that oiling is going to drop off between 6000 and 6500 RPM. You could try reving to 6250 and doing a UOA, then going all the way.

As far as a technical discussion about engine design here, heh... This ain't no LS1Tech.

 

[got one]

Tony, don't know if you misunderstood my post. I didn't know if you were looking for an actual answer, based on experience, or speculation from us. A sole member might have information on his particular failure, whereas a shop would have information on multiple failures. Plus, most vendor's (UGR, Heffner, Hennessey) are trying to find the limits of these motors, not Joe Blow in his garage changing an air filter to a K&N.

If you really want to know, I'm sure most shop's wouldn't mind answering a question that would take a couple of minutes to answer (via the phone). I don't see how Mark Jorgensen coming here and spending a total of 1 hour posting back in forth via forum conversation is going to be more cost-effective than you calling him up and talking to him. That's just me.

I may have mistaken your post as looking for solid information, when you were merely looking for "discussion". Sorry

J

You coming down for the 13th? Nineball?

Tator might know on this one...or maybe Jon B...they might not have picked up this thread yet though...

 

[Malu59RT]

J

You coming down for the 13th? Nineball?

Tator might know on this one...or maybe Jon B...they might not have picked up this thread yet though...

Ryan, I didn't even know of the event till I just went and looked. I wish I had known a little more in advance, I would have definitely come down, but I have a prior engagement. This *****

Jason

 

[Nine Ball]

Ryan, didn't know about the 13th gathering. I won't be able to make it. Funny, I'll be in Austin this weekend though. Family member graduating UT.

Tony

 

[ILLSMOQ]

MikeR had a tune in his car for about 4 months with his rev limiter set to around 6800 I believe. He wouldn't take it past 6400 but it did fine....then he sold the car.

A&C did the tune, I'd ask Todd....I'm also interested, I hit the rev limiter once in a while.

 

[Nine Ball]

Okay, I spoke with Hennessey since he is local and knows me. He was helpful, and explained the limitations of the engine.

Apparently, the oiling system will starve rod bearing #3 on the crankshaft if the engine is spun beyond 6,000 rpm. The valve springs are also not good enough to prevent valve float. So, spinning it beyond 6,000 could cause you to spin a rod bearing, and then snap a rod and send it through the side of the block. John said ~730 rwhp with a very good tune would be the max he would ever push on a stock longblock. 700 rwhp safely. I'll probably just get custom dyno tuning done to smooth out my midrange, it feels kind of sluggish until 4500 rpm. I'm just using the stock Split Second that came with the Paxton.

Summary: Oiling system and valve springs

 

[F8L SNK]

Tony,

You can get the 08 Oiling system for the 06 motor. This will address the deficiencies in the 06 system. It will come with a new oil pump, front cover, oil pan, pickup etc... As far as the springs go, you know how easy they are to change so that is a non issue. Flow, Greg Good. But at the end of the day there is only so much you can do with that big ass heavy crank shaft. It is just too much weight to spin high. Obviously a new crank can be made, but I know you are looking to keep it more basic than a motor build.

I have also heard that the 08 heads and intake are being adapted to work on the pre 08's. I don't remember who was working/researching this. The 08 intake manifold flows way better than the 06 and the heads do as well. I know John H has already ported the 08 heads as well. The 08's already are capable of 6,500 rpm.

Hope this helps a little.

BTW, saw your car today with the hood. Looks good. I was dropping mine off when Chris was pulling your car out of the building. Still not sure how yours got done first when my hood was there 2 months before yours

 

[Nine Ball]

Tim, I saw your car in the spray booth today when I picked up my car. Chris almost loaded your silver striped hood into my truck, lol. I wondered how it would look with the grilles missing, I didn't like it. Grilles ordered

 

[Tiago]

Tim,

what are you revving the 06 car to?

 

[Boxer12]

its a truck motor...adjust your thinking accordingly...

 

[F8L SNK]

Tony, I already hove my grills in the garage! Glad to hear the car was in the spray booth. Could you tell if they started the stripes yet?

Tiago, I shift the 06 at 6,100 It is still making power above that, but the increased stress on the motor is not worth it to me. I feel comfortable with 6,200 - 6,300 but we chose to put the limiter on 6,200.

 

[Nine Ball]

No stripes on your car in the booth, but they did have the '08 hood installed already. It only took them a day to turn mine around, yours will probably be done tomorrow afternoon. My garage smells nice now, fresh paint.

 

[F8L SNK]

It looked really good, I am excited to get mine back. Let me know when your going to the track next too!