How do you think the stage 1 blower cam will work in a 5.3L with flat top pistons? Looking at getting a 5.3 here soon and have some flat top pistons I may throw in it. Possibly going supercharger later on but not right away.

 

Great info Martin. Looking towards one of your cams for my 5.3 on my crew cab soon.

 

I think this is fact ^^^. But, since it is less than a 10% difference in displacement, it may not be as significant as some assume.

 

thanks 4 the info ! i learned something

 

It would work even better than in a dished piston motor. The added compression will only wake the motor up even more. Throttle response, drivability and power will all be much better with more compression.
Let me know when!
Tigger, bore honestly doesn't play as big of a part as you would think even when the difference is more than 10%. Where the piston is in relation to TDC and BDC and the valve events it correlates with are the deciding factors along with port volume, port length, runner length, runner volume, plenum volume and intake valve sizing.

Did you see the graphs I posted with the 6.0 with a 4.0" bore compared to a 5.3 with a 3.78" bore? They both have the exact same IVC event and peak at the exact same rpm for torque and horsepower. How else can you explain that?

The only affect the smaller bore drawing less vacuum and allowing less air to enter the motor has is on power output, not where the engine peaks at.

This is just some of the things I've found from doing literally over 500 cams since I've been at Tick Performance. I know some may not believe that number, but it may be even higher by now. I lost count around the 300 mark.

 

 

Sounds real nice!!

 

Did both of those motors have the same heads and intake? Same headers?

If the smaller motor has smaller heads and/or smaller intake, your test them becomes invalid. GM put smaller heads on the smaller motors for a reason. To maintain a certain displacement to head volume/flow ratio.

An engine is a positive displacement pump. Bore to stroke ratio and rod to stroke ratios certain have an influence over torque curves and cam timing preferences, but in the end an 350 cubic inch pump still pumps 350 cubic inches of air per cycle at 100% volumetric efficiency. And when that pump changes to 320 cubic inches per cycle, it will reach optimum volumetric efficiency at a higher RPM when all other things are equal.

But, again, there is a 10% difference in displacement between a 5.7 and a 5.3. Not much to worry about IMO.

 

Both engines had the same intakes and same 1x7/8" headers. BTW you keep saying 5.7 like the graph I posted of a 4.0" bore engine is a 5.7. Well if you can input the parameters for cubic inches you would find that a 6.098" rod length, 3.622" stroke and a 4.0" bore with 8 cylinders equals 364 cubic inches which makes it a 6.0. Not a 5.7. That's a 40 cubic inch difference in the two and they STILL peak at the same RPM. A 5.7 has a 3.898" bore.

I've tested this numerous times. A 5.3 and a 5.7 or a 5.3 and a 6.0 will all peak within 50-100rpm's for a given intake valve close event if the manifold and cylinder head runner length is the same and cross sectional area is close to being the same.

BTW a smaller head will peak at a LOWER rpm, which a 5.3 head has a 190cc intake runner and a 1.89" intake valve. A 6.0 which is the graph I posted not a 5.7 has a 210cc intake runner and a 2.0" valve. Which means it should peak later by your reasoning. Tell me why it doesn't in this case? Both have the SAME headers and SAME intake...so why do they not peak at different rpm?

 

The 5.3 has the smaller runner 5.3 head and the 6.0 has the larger 6.0 head right? If this is the case, then the heads are proportionate to the displacement of the engine. This would lend itself to the results you have. However, put that bigger head on the small engine and the smaller engine will need to run at a higher rpm to reach optimum volumetric efficiency.

My experience with engines ranging from big block Chevies with rectangular port heads vs oval port and small block Fords with Cleveland Vs Windsor heads almost always show the same thing. A small engine with a big head wants a narrower LSA and more ICL advance to acheive optimal average power under the curve vs a bigger motor with a smaller head that most often prefers a wider LSA with less ICL advance. There is no reason this would not also be true for an LS series engine.

I think the ultimate extreme example to illustrate the point would be a comparison between and LS3 and a 5.3 with LS3 heads (if you could make em fit). They both have the same stroke and stroke to rod ratio, however I am willing to bet that the 5.3 would need a smaller cam with narrower LSA and an earlier IVC to make optimal average horsepower in the same RPM same range. This has proven true throughout time on all types on V8s.

One thing that the LS has going for it that can mask a less than optimal cam choice is the long runner LS EFI intake. That intake has allowed many guys to over cam their engines and still get acceptable results. Get the cam that wrong on a car equipped with a Victor Jr. and you will have your very own pet pig.

 

Tigger,

I am not arguing that cam specs need to be slightly different for each engine, I am only illustrating, in all of my testing and from all the results I've personally gathered from my camshafts that I have done that when you're dealing with port volumes that vary so little from a 190cc port to a 210cc while the stroke and rod length remains the same and the intake valve closes at the same time on each engine that the peak rpm will not change.

I'm not arguing that a 260cc runner head will need a different cam than a 190cc runner head that the 5.3 came with of course it will. BUT when you have a 6.0 and a 5.3 or a 5.7 and a 5.3 that have NEARLY IDENTICAL port volumes with the same rod and stroke length the cam and intake valve closing event will be NO different from the one used in the opposite engine. Or at least I feel it should be. I wish I had a dyno graph for every engine I've cammed. I could show you at least 10 more examples just like the two I've shown in this thread.

All I am saying, is if the 5.3 needs such an earlier intake valve closing event and shorter events in general than a 6.0 why does it peak at the same RPM. No one can answer that question....I will continue to cam my customers engines the same as I have been doing.

 

I would bet a lot of what you are seeing has to do with those tuned long runner intakes.

 

I have some customers with carb'd 5.3's in the works along with some customers with carb'd 6.0's in the works with single plane intakes. 3-4 of them have the same IVC event as the other(5.3 vs. 6.0). If any of those customers put them on a dyno(most of my carb customers could care less about dyno numbers they want to race like yourself) I'll make a separate thread illustrating the similarities.

 

I would say a 5.3l is equivalent to a LT1 in the power department when swapped into an fbody or ybody

 

So explain why would an XER lobed 223/228 106/106 in a 10.5-1cr wearing stock ls6 heads, stock ls6 intake/tb and 1 3/4 headers peaked exactly where a stock ls6 cam does.. There is a reason why I put that cam in a specific vehicle.

 

That is a drastically different design of a camshaft. There is a lot of variables there. It may peak at the same place but I bet it has a hell of a lot better midrange. Am I right?

 

Soo much damn good information on here. Thats all I gotta say. Keep it going guys. Lol

 

TOTALLY great info! Technical information with proof to back it up is exactly what my analytical style brain needs! Thank a ton!

I am building a budget carb'd 5.3. Totally stock for now, but cam, valvetrain and head upgrades are all in the future. Everything you are posting is terrific! I would really apperciate it if you could create a carb/cam dyno thread. Seeing the real world outcomes of different combination would be a great part selection tool for all of us! Thanks Martin!

 

Great points made. That said both have the same 55 degree exhaust valve opening event before bottom dead center. Only difference is the IVO and EVC events.

I use all the data I've gathered for future reference on all the cams I do. This is what I have found from that data nothing more. It's worked so far, I think I will keep doing it this way. Good discussion though.

I told Tooley one time that I had noticed that with identical cam timing events in identical engines other than EVC being 2 degrees later(my V.2 112lsa Polluter versus V.2 111lsa Polluter) 2 degrees more overlap carried power to a higher rpm power peak. He disagreed that it was from the overlap lol. He has told me plenty of times before that EVO, IVO and EVC have little to no effect on where power actually peaks, but how the curves are formed(i.e. plotted) and how they fall after peak. I forwarded him a link to this thread. Maybe he will grace us with his presence.
Which LS6 cam? 204 intake duration or the 207 intake duration? Everything the same on both engines? Or did you do a cam swap from the stock LS6 cam to the 223/228 106/106 cam?

 

Here is a mind boggler for Lil SS and Tigger since both think that a larger engine will peak sooner and a smaller engine will peak later with identical cam timing events all other variables being identical.

This is what I noticed and mentioned to Tooley and he disagreed. I still think that just like Bozz Hawg said that overlap can help carry power further past peak, but I still am left wondering if it actually affects where power peaks and not just before peak and after peak. I mean, I can look at this graph and say, "The only different variables in this equation are a 10cc difference in port volume(from my experience not near enough to change power peak, but it's possible) and 2 degrees of overlap." That still isn't a firm enough stance for me. I'd need to see at least 4-5 more engines with these two cams in them with every other variable being the same as it was in this case to draw a conclusion. It took at least 7-8 5.3 cams for me to realize and ask myself..."Why are these 5.3's peaking so early with these cams?" So I asked an esteemed colleague of mine what he thought and his advice was, "Cam the 5.3 with the same IVC as a 5.7/6.0 and watch what happens." So I did and saw that for the same IVC event as I was using in the larger bore engines, once used in a 5.3 engine with a smaller bore, it produced the same peak power rpm as the larger bore engine did.

LS1(3.898" x 3.622") with the 239/244 112+3 V.2 Polluter. Events are:
10.5 IVO
48.5 IVC
57.0 EVO
7.0 EVC

LS2(4.0" x 3.622") with the same 239/244 V.2 Polluter but on a 111+2...events are:
10.5 IVO
48.5 IVC
55.0 EVO
9.0 EVC

Here is a graph overlay showing both cams. Blue line is the LS2, red line is the LS1. Notice that the larger bore LS2 actually peaks later(around 5100 for torque and 6450 for horsepower) and not earlier than the smaller bore LS1(around 4800 for torque and 6250-6300 for horsepower).