4+7 Swap
#3
Re: 4+7 Swap
its not all about the power increase...and its a lot more then 1%....if it was a miniscule 10hp on a 1000 hp motor there wouldnt be a need for a 4/7 swap cam...people have seen 15+ on a stockish motor from swapping out an aftermarket cam with a cam of the same specs with the 4 and 7 lobes changed...other then then power increase the motor will run smoother and produce fatter torque curve...go a step further and do a 2/3 4/7 cam swap...ever hear the 6.0 LQ9 truck motor run?....kinda sounds different right...thats because there firing order is in conjuction with the 2/3 4/7 swap...the torque curve is flat as a preteen and you cant even tell the motor is running....
#4
Re: 4+7 Swap
Originally Posted by Vicious95Z28
Just curious if any1 done it. What are the results?
Results are mixed. I don't think anyone has yet figured out the right combination of variables to achieve consistant results.
If you're replacing the cam ANYWAY, such as during a rebuild, then try it.
#6
Re: 4+7 Swap
The 4/7 swap is the only one that makes power.The other swaps just sound good.
The computer issues aren't worth the trouble for the SMALL 1/2 % to 1% gain.
The big thing in a max effort engine is the main brg loading,the 4/7 swap equal's the load out on the mains.
The computer issues aren't worth the trouble for the SMALL 1/2 % to 1% gain.
The big thing in a max effort engine is the main brg loading,the 4/7 swap equal's the load out on the mains.
#7
Re: 4+7 Swap
In Reher Morrison's engine build book they list 8 possible firing orders for V8 engines. They go on to say that they have tried & extensively tested most of them. The 4/7 swap, according to RM was worth 5-8 hp on their PS engines (~.5%).
I can only tell what I've seen and I always narrow that down to the ones I've had some intimate knowledge of. Most of the guys I know who are trying 4/7 or even 4/7 2/3 swaps are only seeing a little less bearing wear & not much, if anything in the way of ET reduction. The engines "feel smoother down the track" but that's about it.
One other guy who does this stuff for a living says his BBC logs more uniform EGT's but he's still running within a tenth of where he was with the std. firing order.
I haven't heard of anyone losing power with the swap but I'm still having a tough time quantifying any gains from it. IMO, you're going to need a tri-y 4-2-1 header configuration to really try and take advantage of the swap & that's just another expense most street guys don't need.
I still say... spend your money elsewhere.
BTW- Can anyone link to dynographs of these 10-15hp improvements shown on "stock" engines. I'd like to see what else was changed.
I think you have to really read into this stuff before you buy it. Who knows what kind of gains might have come via a valvespring swap... etc..
-Mindgame
I can only tell what I've seen and I always narrow that down to the ones I've had some intimate knowledge of. Most of the guys I know who are trying 4/7 or even 4/7 2/3 swaps are only seeing a little less bearing wear & not much, if anything in the way of ET reduction. The engines "feel smoother down the track" but that's about it.
One other guy who does this stuff for a living says his BBC logs more uniform EGT's but he's still running within a tenth of where he was with the std. firing order.
I haven't heard of anyone losing power with the swap but I'm still having a tough time quantifying any gains from it. IMO, you're going to need a tri-y 4-2-1 header configuration to really try and take advantage of the swap & that's just another expense most street guys don't need.
I still say... spend your money elsewhere.
BTW- Can anyone link to dynographs of these 10-15hp improvements shown on "stock" engines. I'd like to see what else was changed.
I think you have to really read into this stuff before you buy it. Who knows what kind of gains might have come via a valvespring swap... etc..
-Mindgame
Last edited by Mindgame; 02-27-2006 at 10:18 PM.
#8
Re: 4+7 Swap
Going along with what Mr. Mindgame posted, a lot of information is misleading even if correct. For example, the "gains" some people see after replacing plugs and wires might lead them to conclude that x-brand of wires and plugs are worth y-hp. In reality, all they may have proven is that a new set of plugs and wires is worth more than a worn out set. For gains as small as we are talking about, a very careful testing procedure is necessary wioth all of the other variables eliminated. How many people have done a 4-7 swap with NO other changes and adjusted test results for the conditions, etc.? I am not saying that the 4-7 swap isn't worthwhile, it may be. I just don't know. But I doubt 15-20hp on a stockish motor.
Rich
Rich
#10
Re: 4+7 Swap
Originally Posted by BMoney
the 4/7 swap and the 2/3 4/7, are mainly for engines turning more than like 7500+ rpm's. its has something to do with a more accurate spark at high rpm's to each cylinder.
#11
Re: 4+7 Swap
oh ok thanks, but you might want to look up. Im not the one asking about it, I just gave my opinion on what Ive heard. I had a cam built from LSM and they made the 2/3 4/7 swap no questions asked. I had a small block turning 8800rpm's and that was the reason they said for it. so I apologize
#12
Re: 4+7 Swap
Yea I know,but your assessment of what the swap does is incorrect.It has nothing to do with spark other than changing some plug wires.
Not a slam but more on the lines to get people to study up on these things before a nubee gets the wrong info and takes it as gospel and goes and spends a lot of money on something they don't need.
I ran this swap in the '70's in a dirt track sprint car and found no difference and can't find a reason it would work any better today.
Not a slam but more on the lines to get people to study up on these things before a nubee gets the wrong info and takes it as gospel and goes and spends a lot of money on something they don't need.
I ran this swap in the '70's in a dirt track sprint car and found no difference and can't find a reason it would work any better today.
#14
Re: 4+7 Swap
Originally Posted by SStrokerAce
Can't run the swap on a stock ECU. The fuel tuining would be off since it would only be getting the right signal from 3 of the cylinders on each bank.
Bret
Bret
Totally understood.
#15
Re: 4+7 Swap
Yea, The injector timing would be impossible to change right?
As for spark, you could just switch the wires around ...
I have heard and read that it only eliminates harmonic vibrations.
Which in turn, is easier on the bearings.
Save yourself the time effort and money. Get a good balancer, and call it a day.
Besides the stock PCM wont allow the engine to rev high enough to benfit from it anyways.
As for spark, you could just switch the wires around ...
I have heard and read that it only eliminates harmonic vibrations.
Which in turn, is easier on the bearings.
Save yourself the time effort and money. Get a good balancer, and call it a day.
Besides the stock PCM wont allow the engine to rev high enough to benfit from it anyways.