06 Bu SS 3900 Build

[gectek]

got the trans cooler nearly all done. got 1 wrong fitting, but good thing i work at where i do. quick and easy swap lol. then it will be done as well. put front bumper back on, and its ready to buggie to the shop for the final exhaust work tomorrow morning.

[AaronGTR]

I would be curious as to what the vvt motor could do if they had a cam where they could change the LSA and the valve timing similar to the cam in the latest viper V10. I read something on it once and iirc it has an inner and outer shaft with the intake valves able to change timing relative to the exhaust valves. I bet that would be better than just varying the timing on the whole cam overall.


On topic though, it sounds like quite the build. Looking forward to the results.

[robertisaar]

that would be the chrysler "cam-in-cam" setup... interesting idea, not sure how well it works though.

FWIW: it looks like the stock 3900 cam is fairly weak spec-wise, but it uses the ability of retarding it far enough to make up for it and pull 240/240.

[Joseph Upson]

I would be curious as to what the vvt motor could do if they had a cam where they could change the LSA and the valve timing similar to the cam in the latest viper V10. I read something on it once and iirc it has an inner and outer shaft with the intake valves able to change timing relative to the exhaust valves. I bet that would be better than just varying the timing on the whole cam overall.


On topic though, it sounds like quite the build. Looking forward to the results.

I believe that's Comp Cams invention, I saw a cartoon showing its function on Youtube last year I believe.

that would be the chrysler "cam-in-cam" setup... interesting idea, not sure how well it works though.

FWIW: it looks like the stock 3900 cam is fairly weak spec-wise, but it uses the ability of retarding it far enough to make up for it and pull 240/240.

It may be wimpy duration wise, but it's the area under the curve for that short duration that makes an impact despite that. The lobes look pretty fat. The supercharged 3800 puts out about 280 lb/ft so 242 out of a naturally aspirated engine with .1 more cubes isn't shabby.

I just looked at my second 3900 camshaft considering another regrind but after talking to Delta Cams today and finding out that all they do is find a cam close to the specs you want and trace it, I've changed my mind unless I can find someone that can cut it to specs I determine. I want a more aggressive valve opening rate for more bottom end torque and a little more duration with the same LSA this time. I believe the best approach is just a little improvement on the stock tested and proven cam. I've been dating the high horsepower idea but it's around town stop light to stop light acceleration (not racing) that makes driving the car fun so that's where my focus will be.

[gectek]

then you will go with a fat lobe like an XFI or XER from comp and then use more lift. follow those lines. i believe delta CAN use your specs if you specify. the problem is, without a blank, there is only so much you can do. they do NOT like to weld lobes. they would rather cut the one you have down. the prob is, the hollow cam creates a problem as well. comp will NOT touch a hollow cam. crane used to entertain the idea, but they are not back up and running yet, nor would i trust them. Joseph, if you want i can talk to Cam Motion about regrinding your cam to your specs. No promises, but we do have alot of pull with the cam companies. I have a very good idea as to what they will and will not do.

[gectek]

update on topic lol
car is nearing done. i am waiting to get my camera back so i can take pics. trans cooler is done, it turned out VERY well. loaded car onto trailer and its getting the exhaust done now.

[Joseph Upson]

then you will go with a fat lobe like an XFI or XER from comp and then use more lift. follow those lines. i believe delta CAN use your specs if you specify. the problem is, without a blank, there is only so much you can do. they do NOT like to weld lobes. they would rather cut the one you have down. the prob is, the hollow cam creates a problem as well. comp will NOT touch a hollow cam. crane used to entertain the idea, but they are not back up and running yet, nor would i trust them. Joseph, if you want i can talk to Cam Motion about regrinding your cam to your specs. No promises, but we do have alot of pull with the cam companies. I have a very good idea as to what they will and will not do.

I wouldn't mind you checking into it. My current cam is from Delta and it was talking with them for the second cam that I discovered the grind limitations. They will not weld on the hollow cam, I asked about that and Comp Cams did entertain the regrind option however they would have to look at it first. Their major concern was with depth of lobe hardness which I didn't think would be as big a problem on a roller cam. I'm just looking for the most aggressive street lobe openning rate I can get and single pattern duration of about 215-220. I'm not as concerned about greatly increased lift.

[gectek]

Well i know comp hates hollow core cams. There are a few places that can get what you are looking for, but the ideal thing would be to get a solid core just like that was found by comp cams. they make solid core VVT cams for the LS engines, so i am sure that they can find a place that makes solid cores for the others as well. let me contact them and see what they can find.

[gectek]

Irony is a brand new impala police car is in our service dept. one of the guys tells me about it. so i go look at it. it appears like GM decided to ditch the dual plane upper on this 3900 and also use the exhaust crossover the trans tunnel instead of under the pan with 2 cats. so they did exactly what i did. i find that funny. 09 model

[Joseph Upson]

The single plane intake has been around for a while on the 3900. Probably since 07 when the 3500 went VVT, I do recall seeing it before. Think they did away with cylinder select though which was only available on the Impala and Monte Carlo.

[robertisaar]

The single plane intake has been around for a while on the 3900. Probably since 07 when the 3500 went VVT, I do recall seeing it before. Think they did away with cylinder select though which was only available on the Impala and Monte Carlo.

the cylinder select was a 1 year wonder IIRC... not sure if it was just the Impy, or if the MC could have it as well...

[gectek]

it has not normally been on the 3900. they did put it on the 3500 yes, but they also never offered the dual plane on the 3500. strange i would say. im just putting that out there from all the people asking questions and wondering why i did that.

[bszopi]

it has not normally been on the 3900. they did put it on the 3500 yes, but they also never offered the dual plane on the 3500. strange i would say. im just putting that out there from all the people asking questions and wondering why i did that.

I beg to differ... See photos below of an LZ8 and LZ9. The LZ8 (found in the Impala) doesn't have the rounded plenum like the LZ9.

[gectek]

well, i should have clarified again. in the "perf" apps it was not. sorry. i have spent days pouring over the stuff and my brain is fried, but that is a VERY good clarification as to what is what and what i am aiming for the end product.