5.7 0r 6.1 with msd hemi 6 and carb
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myduster360
Well-Known Member
Its that the carb is "bad" but that the factory intake is often a LOT better. Factory intakes are very well designed.
If you look at the Mopar Muscle link, the LX intake made significantly better midrange Hp and Torque over the MP carb intake. +40Hp/+45ft-lb. imo, thats too much power/trq to give up just to run a carb.
I've spent hours and days at the engine dyno with these new Hemi's. They normally like between 19-21 degree's.
I also read the Mopar Muscle artical. I didn't like the fact that they hogged out the MP intake before testing it. Anyways, I did however test out a factory 5.7 intake, 6.1 SRT8 intake and and an XV intake at the dyno one day. Test's were performed on a 418 stroker with 5.7 heads. The 5.7 and 6.1 intake were pretty much neck and neck. The XV was low on hp/tq throughout. I have one regret is that I didn't spin the XV any higher.
I also read the Mopar Muscle artical. I didn't like the fact that they hogged out the MP intake before testing it. Anyways, I did however test out a factory 5.7 intake, 6.1 SRT8 intake and and an XV intake at the dyno one day. Test's were performed on a 418 stroker with 5.7 heads. The 5.7 and 6.1 intake were pretty much neck and neck. The XV was low on hp/tq throughout. I have one regret is that I didn't spin the XV any higher.
jeffneal66
Well-Known Member
Thanks for sharing that information, that will help answer some basic questions we all have when thinking about modifying these engines. Were the 5.7 heads ported at all?
Jeff
Jeff
Yes they were. CnC ports with 2.05" intake and 1.57" exh valves. The chambers were widened out to match the 4.055" bore of the 6.1.
myduster360
Well-Known Member
Exceptional info. Thank you!
I was wondering how the XV stacked up against the stock intakes.
Looks like the XV is down a good 40hp/40ft-lb similiar to MM test of the MP manifold.
Map63Vette
Well-Known Member
Anyone ever done any testing with the Indy Mod Man setup? I assume it would probably suffer the same fate of the XV and Mopar Performance carb style intakes with the shorter runners, but I was looking into running one since they seem to be one of the most affordable carb options. I still find it odd that you can get a dual quad Edelbrock setup for far less than a single quad XV setup...
ateam
A motor can
Going a different direction with (2) 2bbl tbi's(GM) and GM controller #1227747, to be reflashed by possibly "Moates.net". Yes they woun't look like carbs, but they will have a "Hemi Shaker" on top.I'll let the dyno sort it all out. ateam:|
This thread is going to be very helpful to a lot of people and I thank all of you,PLEASE KEEP THE INFO COMING !!!!!!! I'm open to any suggestions to remedy my situation,and i appreciate the responses,Still i ask does anyone out there have a hemi-6 with the xv intake and single carb in a car and running???????? I fell almost like a Guinna pig for xv,also look forward to testing the Indy mod man set-up to see what it results are. This is a great testament to how this site rocks!!!!!
Yes, I'm part of the Sharadon team.
Map63Vette
Well-Known Member
I know XV sells kits for their conversion pieces that are "pre-tuned". I'm not sure how good that tuning might be, and I'm sure they wouldn't give you the exact numbers, but you might consider calling them to see if they can give you an idea about your timing issue. They may at least be willing to divulge some timing numbers to see if you're on the right track.
Thanks--Already delt with Peter at XV after the car was fired up,I think peter was a top notch guy and XV was good to deal with but he and XV have a easy out of coarse they never had these problems and sent me to M.S.D and that also was a dead end,I think i have covered my bases thats why i put this out here. Steve
myduster360
Well-Known Member
swifter,
How more power was made between using, say 25 degrees vs 42?
are we talking 10hp or 25hp?
Can you post pics of your dyno graphs?
email me your MSD file
[email protected]
How more power was made between using, say 25 degrees vs 42?
are we talking 10hp or 25hp?
Can you post pics of your dyno graphs?
email me your MSD file
[email protected]
Rat Patrol
Well-Known Member
Just read through this thread and it stops at a dead end -
I don't want to re-open old wounds but could the OP or someone else advise if the timing debate and power loss was resolved?
As I may well be doing this type of conversion shortly - Id like to know if there was a component issue or if it was resolved through tuning?
I don't want to re-open old wounds but could the OP or someone else advise if the timing debate and power loss was resolved?
As I may well be doing this type of conversion shortly - Id like to know if there was a component issue or if it was resolved through tuning?
Map63Vette
Well-Known Member
From my experience when I had a carb on top of mine before I went back to EFI the timing seemed to be a little funky. I could throw mountains of timing in without ever hearing knock, but I think part of that was because my carb tune was on the lean side since I didn't have enough jets on hand to try to get it right. That's not saying that I was making any more power with the extra timing, just that it didn't seem to be hurting anything. I think part of the issue may have been that I was using a stock cam (designed for EFI) with a carb, so the carb may not have been getting the best sort of vaccuum signal. I think I bumped up the top end maybe 3-4 degrees from the base MSD map. It seemed to like it, though I never had a dyno to prove it. Most people that have put carbs on top seem to get away with the extra timing for some reason.
USCG CHARGER
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Monday I'll be redynoing my car. I currently only have 6* of timing b/c we couldn't read the PIDs so we wanted to be on the safe side. As mentioned before I think I will see between 18-21* of total timing when it's all said and done.
When I look at these timing tables the MAP readings look backwards in relation to the ignition timing , 105 KPA = 31 inHg , 10 KPA = 2.95 inHg . You need more timimg at light load (high manifold vaccum) , less timing at full load ( 0 to low manifold vaccum ) . Am I reading something the wrong way here?These are the factory MBT timing tables. These timing values represent the Mininmum timing advance that delivers the Best Torque.[MBT] These values also assume that the engine is NOT knock limited in any way ei: its using high octane fuel.
The PCM uses these values as a CAP or MAX to the final timing.
WOT timing for pump gas is usually a couple degrees lower.
Unless you're on a dyno measuring the HP gain/loss of timing adjustments while monitoring Knock, I'd NEVER go any higher than these values.
2005 5.7L
2007 6.1L
Joe Dokes
Well-Known Member
Swifter,
I think if you read the attached article posted by Joe Boy, you'll see that the plastic 5.7L Hemi manifold had between 10 and 40 HP advantage over the single plane MP manifold from 4000 to 6000 RPM. Only at 6500 RPM did the single plane MP manifold begin to make more power, and then it only made 6 HP more. In terms of torque the power gains were even more substantial, again the single plane manifold only gains an advantage beginning at 6500.
As far as a carb being the "worst" thing you can do to a hemi, that is clearly hyperbole. I think a more accurate description of a carb on a modern hemi is that if you choose to go that route your leaving "free" HP on the table.
At one time carbs had a distinct advantage over fuel injection particularly in race applications. I think fully programmable fuel injection setups have negated that advantage. In my view here are advantages of modern port fuel injection.
1. Fuel injection manifold design considerations only have to balance port cross section for sufficient air flow and velocity. While carburetor manifolds also have the challenge of ensuring that fuel stays atomized, carburetor manifold designers have to worry about fuel dropping out of suspension and creating lean cylinders and the resulting loss of power. This advantage of a dry manifold can be clearly seen in the Eagle 5.7l hemis, they have variable intake runner length, this allows a truck hemi to have 390 HP and 400 Ft. Lbs. of torque out of 345 cubic inches.
2. Carbs have to be sized small so that engine vacuum can send a signal to the carb, while fuel injection motors don't need to rely on a strong vacuum signal to the carb. Fuel injection can be programmed to respond to a very weak manifold signal. The result is carbs for a 5.7L Hemi range in size from 625-750 CFM. Any bigger and the motor would be a dog on the bottom end. All Hemis come with an 80mm throttle body capable of flowing over 900 CFM.
3. At one time a big advantage that carbs had over fuel injection was that you could run a lot bigger cam with a carb than you could with fuel injection. However if you go to fully programmable fuel injection that is capable of Alpha N programming you can run as radical a cam as you like.
All that being said, I've moderated my views regarding carbs on a modern hemi. I still think EFI is the way to go, but I've seen too many very nice running GenIII Hemis with carbs and owners who are completely happy. Who am I to look at someone completely satisfied and say they're wrong?
Regards,
Joe Dokes
I think if you read the attached article posted by Joe Boy, you'll see that the plastic 5.7L Hemi manifold had between 10 and 40 HP advantage over the single plane MP manifold from 4000 to 6000 RPM. Only at 6500 RPM did the single plane MP manifold begin to make more power, and then it only made 6 HP more. In terms of torque the power gains were even more substantial, again the single plane manifold only gains an advantage beginning at 6500.
As far as a carb being the "worst" thing you can do to a hemi, that is clearly hyperbole. I think a more accurate description of a carb on a modern hemi is that if you choose to go that route your leaving "free" HP on the table.
At one time carbs had a distinct advantage over fuel injection particularly in race applications. I think fully programmable fuel injection setups have negated that advantage. In my view here are advantages of modern port fuel injection.
1. Fuel injection manifold design considerations only have to balance port cross section for sufficient air flow and velocity. While carburetor manifolds also have the challenge of ensuring that fuel stays atomized, carburetor manifold designers have to worry about fuel dropping out of suspension and creating lean cylinders and the resulting loss of power. This advantage of a dry manifold can be clearly seen in the Eagle 5.7l hemis, they have variable intake runner length, this allows a truck hemi to have 390 HP and 400 Ft. Lbs. of torque out of 345 cubic inches.
2. Carbs have to be sized small so that engine vacuum can send a signal to the carb, while fuel injection motors don't need to rely on a strong vacuum signal to the carb. Fuel injection can be programmed to respond to a very weak manifold signal. The result is carbs for a 5.7L Hemi range in size from 625-750 CFM. Any bigger and the motor would be a dog on the bottom end. All Hemis come with an 80mm throttle body capable of flowing over 900 CFM.
3. At one time a big advantage that carbs had over fuel injection was that you could run a lot bigger cam with a carb than you could with fuel injection. However if you go to fully programmable fuel injection that is capable of Alpha N programming you can run as radical a cam as you like.
All that being said, I've moderated my views regarding carbs on a modern hemi. I still think EFI is the way to go, but I've seen too many very nice running GenIII Hemis with carbs and owners who are completely happy. Who am I to look at someone completely satisfied and say they're wrong?
Regards,
Joe Dokes
Rat Patrol
Well-Known Member
I'm struggling to read the charts that were posted up - what would be a "safe" WOT timing figure to start with assuming AF is safely in the mid 13s ?
Hi RatPatrol them charts almost look like they are for a boosted motor to me because of the positive MAP readings , i've used plots for progamable ignition only, so they look different to this , so maybe i'm missing something.
Anyhow what people seem to be saying here is around 22 degress for wide open throttle max RPM with sequential injection , perhaps a little more for a carbed Hemi , maybe they need to be a bit richer to allow for less precise fuel distribution ' my guess ' .
I think safe AFR's on a carbed motor would be more like mid 12 to low 13 .
Anyhow what people seem to be saying here is around 22 degress for wide open throttle max RPM with sequential injection , perhaps a little more for a carbed Hemi , maybe they need to be a bit richer to allow for less precise fuel distribution ' my guess ' .
I think safe AFR's on a carbed motor would be more like mid 12 to low 13 .
Rat Patrol
Well-Known Member
Ok thanks mo-cars.
Those AFRs are almost the same as a cast iron headed small block.
What do you think the cruise total timing should be limited to..........I've heard 50deg which seems pretty high...........
Those AFRs are almost the same as a cast iron headed small block.
What do you think the cruise total timing should be limited to..........I've heard 50deg which seems pretty high...........
Map63Vette
Well-Known Member
I think as far as carb vs EFI on the new Hemi that the problem really lies in the manifold, not the fuel distribution method (as seen on the graphs). Theoretically speaking both can make the same power, granted EFI can make more power more often because it can adjust to environmental changes, but there hasn't really been much for development on carb intakes. The huge high rise drag pack setup might help to even the playing field, but you're not going to fit that under a stock hood without setting the engine on the ground, lol.
As far as cruise timing I think the stock MSD setting is around 42-45 degrees, which I know I've run at without issue. 50 does seem a little on the high side. You can always set it low and just slowly creep up the setting to see how it responds. You really don't need tons of cruise timing unless you're really trying to lean it out for gas mileage.
As far as cruise timing I think the stock MSD setting is around 42-45 degrees, which I know I've run at without issue. 50 does seem a little on the high side. You can always set it low and just slowly creep up the setting to see how it responds. You really don't need tons of cruise timing unless you're really trying to lean it out for gas mileage.
Joe Dokes
Well-Known Member
Excellent point Map63vette! Although I think the dragpak manifold is too tall for most applications, I'd love to see some dyno numbers to see how it performs on both an injected and carbureted motor.
HemiUp, thanks for posting some first hand knowledge of the limitations with the XV intake manifold help to clarify some of the choices.
Does anyone have any experience with Individual Throttle Bodies from the likes of Hilborn, Borla (formerly TWM), and Extrudabody? I wonder if being able to adjust the length of the ram tubes would give the ability to gain more top end while preserving mid range torque that many of the single plane manifolds seem to give up? At the same time all the factory intake manifolds seem to run out of steam around 6000 RPM.
Finally, according to this article on MS3 and about 22 degrees of advance at WOT is about the max for this motor. For those who've run 50 degrees, me thinks there might be some other issues in your setup. I've never seen a motor run well on 50 degrees of advance.
http://www.diyautotune.com/tech_articles/how_to_megasquirt_your_new_hemi.htm
Regards,
Joe Dokes
HemiUp, thanks for posting some first hand knowledge of the limitations with the XV intake manifold help to clarify some of the choices.
Does anyone have any experience with Individual Throttle Bodies from the likes of Hilborn, Borla (formerly TWM), and Extrudabody? I wonder if being able to adjust the length of the ram tubes would give the ability to gain more top end while preserving mid range torque that many of the single plane manifolds seem to give up? At the same time all the factory intake manifolds seem to run out of steam around 6000 RPM.
Finally, according to this article on MS3 and about 22 degrees of advance at WOT is about the max for this motor. For those who've run 50 degrees, me thinks there might be some other issues in your setup. I've never seen a motor run well on 50 degrees of advance.
http://www.diyautotune.com/tech_articles/how_to_megasquirt_your_new_hemi.htm
Regards,
Joe Dokes
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