Another 98 Cobra Intake Cam Topic

[torched04]

I just wanted to add to pull all your lash adjusters when you yank the cams and bleed them down to verify you have no collapsed adjusters and no lash adjusters that stay rock hard.

Having collapsed or rock hard adjusters are going to screw up valve seal and cam performance as well so its something to look at.

For reference I have about 12 adjusters left to check on my brothers motor and so far 3 have been collasped and 2 hard as rocks and won't bleed down... those are going in the garbage can.

Something to look at.

[tmhutch]

Originally Posted by uscstew

not degreed (intakes were at 119 and exhausts were at 114 when checked) the car made 300ish hp and 285ish tq. peak power at 6600ish

degreed (intakes at 108 and exhausts at 117) the car made 300ish hp and 320ish tq. peak power was at 6100ish.
the only difference between the 2 dyno sessions was the cams being degreed. like i said, i will try to get graphs to get exact numbers and differences.

Great, genuine before and after numbers. Thank you for posting them. The differences do seem a bit dramatic but valuable information to have in any case.

As has been said a few times, some long tubes would work nicely. Especially with the additional overlap you now have with the tighter lobe centers.

[torched04]

Originally Posted by tmhutch

Great, genuine before and after numbers. Thank you for posting them. The differences do seem a bit dramatic but valuable information to have in any case.

As has been said a few times, some long tubes would work nicely. Especially with the additional overlap you now have with the tighter lobe centers.

No overlap with those cams, but he did tighten it up from -33 to -25, just not enough duration at 204 to give you overlap.

Cool to see the results. I wonder if he would have gained more going with a lower exhaust centerline like 110.

[tmhutch]

Originally Posted by torched04

No overlap with those cams, but he did tighten it up from -33 to -25, just not enough duration at 204 to give you overlap.

Thanks for catching that!

[uscstew]

like i said, im trying to learn this stuff. i understand the how to's, but the why to's i am trying to learn. my buddy is supposed to send me a picture of the 2 graphs tomorrow. i thought my numbers were low but im not very experienced in this. thought some of these other guys may know some tricks that im unaware of or something. figured stock intake and manifolds played a little part but not 25rwhp. guess i will have to try it out.

i dont understand why i was told to put them at 108in and 116ex, or why/what 110ex would do. like i said, im trying to learn the whys on things.
what did torched04 mean by "he did tighten it up from -33 to -25"?

[torched04]

Originally Posted by uscstew

like i said, im trying to learn this stuff. i understand the how to's, but the why to's i am trying to learn. my buddy is supposed to send me a picture of the 2 graphs tomorrow. i thought my numbers were low but im not very experienced in this. thought some of these other guys may know some tricks that im unaware of or something. figured stock intake and manifolds played a little part but not 25rwhp. guess i will have to try it out.

i dont understand why i was told to put them at 108in and 116ex, or why/what 110ex would do. like i said, im trying to learn the whys on things.
what did torched04 mean by "he did tighten it up from -33 to -25"?

The overlap is the portion of the cam cycle where the intake is still open and the exhaust is open. One valve is closing and the other is opening.

There is a good illustration if you scroll down on this page - http://www.google.ca/imgres?imgurl=h...ed=0CEYQ9QEwCg

So a negative number means you have no overlap. When I said you tightened them up you went from really wide to less wide, but still don't have overlap. With low duration cams you won't get overlap.

na svt and 03steve(on modfords) have helped me a lot with trying to understand and learn this stuff and figuring out where to set my 97 cobra cams on my build.

I think I am going 108-110 intake and 114-116 exhaust. I run a 3.4 whipple so maybe opening the exhaust valve early might help, but I don't know.

Tighter LSA(say 108 intake and 108 exhaust will give you a 108 LSA) should build more cylinder pressure then wide LSA(stock is 114 assuming the gears are perfect ). You are filling the chamber sooner with air charge.

[tmhutch]

Originally Posted by uscstew

like i said, im trying to learn this stuff. i dont understand why i was told to put them at 108in and 116ex, or why/what 110ex would do. like i said, im trying to learn the whys on things.
what did torched04 mean by "he did tighten it up from -33 to -25"?

No worries, Stew. Cams are one of the most confusing aspect of any engine. Like Torched said, changing the lobe centers changes the lobe separation angle (LSA) and subsequently overlap. I will clarify though, tightening the LSA doesnt neccessarily mean a change in cylinder pressure. You could have change from a 114 to a 110 and have lower cylinder pressure. Advancing the intake lobe is the only thing that changes dynamic compression/cylinder pressure when speaking of cam timing. I posted THIS link a few pages back. It's something I wrote specifically to clarify any and all cam timing questions. You might find it useful.

Todd

[nickmckinney]

Originally Posted by torched04

I think I am going 108-110 intake and 114-116 exhaust. I run a 3.4 whipple so maybe opening the exhaust valve early might help, but I don't know.

Opening the exhaust valve earlier cools everything down better with a boosted car.

[Bmeagher]

Here's a excellent example of adding longtubes and a psri!
http://www.svtperformance.com/forums...y-16-09-a.html

[ModularSpeed]

Originally Posted by Bmeagher

Here's a excellent example of adding longtubes and a psri!
http://www.svtperformance.com/forums...y-16-09-a.html

I would guess the 03+ headed engine would see slightly more gains when adding those mods, and having 96-98 cams.

I would guess the OP would see somewhere around 15-20 RWHP from LT's and a nice intake.

With the March UD Damper/Alt pulley...some more tuning...LTs/Intake....I can see it making over 330 for sure.

[Zack]

Originally Posted by ModularSpeed

I would guess the 03+ headed engine would see slightly more gains when adding those mods, and having 96-98 cams.

I would guess the OP would see somewhere around 15-20 RWHP from LT's and a nice intake.

With the March UD Damper/Alt pulley...some more tuning...LTs/Intake....I can see it making over 330 for sure.

Remember the car is a marauder with an auto. It has longtubes and ud pulleys already and made. 304rwhp and 310+tq before he brought me the car.

[ModularSpeed]

Originally Posted by Zack

Remember the car is a marauder with an auto. It has longtubes and ud pulleys already and made. 304rwhp and 310+tq before he brought me the car.

Oops, I was referring to uscstew

[uscstew]

Originally Posted by Bmeagher

Here's a excellent example of adding longtubes and a psri!
http://www.svtperformance.com/forums...y-16-09-a.html

thats good info. it would be nice if mine would carry out the power like that instead of falling off at 6100.


looks like i am going to be doing A LOT of reading for the next day or two. thanks for the links guys.

[nickmckinney]

Originally Posted by Bmeagher

Here's a excellent example of adding longtubes and a psri!
http://www.svtperformance.com/forums...y-16-09-a.html

I used the "wayback" machine to find Naz website but all the pictures are missing. Would be nice to see how he was doing his PSR with all the inserts and such that were described.

[na svt]

he used some metal air horns and glued them to the shortened runners...not the best way to do it but it was effective. In one of his descriptions he stated, "fully radiused inlets" but that was bull as you can see in the pics there is no radius (rolled lip) at all. Here's a link to some pics:
http://www.svtperformance.com/forums...nstructed.html

[nickmckinney]

Originally Posted by na svt

he used some metal air horns and glued them to the shortened runners...not the best way to do it but it was effective. In one of his descriptions he stated, "fully radiused inlets" but that was bull as you can see in the pics there is no radius (rolled lip) at all. Here's a link to some pics:
http://www.svtperformance.com/forums...nstructed.html

Thats a good link, thanks. Whats your thoughts on using a flat bottom for the plenum rather than the upwards curved stock one? Looks like a way to add more plenum volume in the area it might be able to actually use it.

[na svt]

Originally Posted by nickmckinney

Thats a good link, thanks. Whats your thoughts on using a flat bottom for the plenum rather than the upwards curved stock one? Looks like a way to add more plenum volume in the area it might be able to actually use it.

I don't bother reducing the plenum volume. The flat bottom is a PITA to make and you have to get a piece thick enough so that it doesn't present the same problems as Naz's intakes.

[tmhutch]

The plenum floor angle should match the angle of the port opening. Flat is not bad but not the best.

[uscstew]

i was wrong on my peaks, but here is the graph

[ModularSpeed]

Holy......

P10SR......and that thing would kill it!!!

[nickmckinney]

Originally Posted by uscstew

i was wrong on my peaks, but here is the graph

Sorry for asking, what again was the difference in this graph?

[nickmckinney]

Originally Posted by tmhutch

The plenum floor angle should match the angle of the port opening. Flat is not bad but not the best.

Is there anyway to extend it downward? It seems the space issue is more at the front and back like the water pump area. Otherwise there is a ton of space directly beneath it if you don't use the stock heater coolant return (obviously this is race car only thinking).

[tmhutch]

Originally Posted by nickmckinney

Is there anyway to extend it downward? It seems the space issue is more at the front and back like the water pump area. Otherwise there is a ton of space directly beneath it if you don't use the stock heater coolant return (obviously this is race car only thinking).

In the front is the alternator and wiring loom but if a person was really determined they could step the plenum down slightly from the stock ceiling area and get a little in front. The rear is encumbered by hoses and wiring as well. It would be alot of trouble for little gain. It is possible to extend the plenum down. With a little grinding on the block (coolant hose is not a problem), 1.5" additional plenum can be fitted and there is a few horsepower there.

[na svt]

For those that believe the stock cams are pretty close to 114/114, here's another data point. This is an 03/04 that was checked yesterday, it too is getting 96-98 intake cams:
Passenger side intake = 111.5
Passenger side exhaust = 110

Driverside intake = 119.5
Driverside exhaust = 108

This is why you see the great differences in power between degreed and undegreed.

Originally Posted by nickmckinney

Sorry for asking, what again was the difference in this graph?

96-98 intake cams, undegreed and degreed to 108 ILC...I think. reference this post:

Originally Posted by uscstew

i have some numbers from 97 cobra cams put in a 03 mach before and after degreed. ill have to see if i can get dyno graphs. my car did not make near the power as these other guys. ...not degreed (intakes were at 119 and exhausts were at 114 when checked) the car made 300ish hp and 285ish tq. peak power at 6600ish

degreed (intakes at 108 and exhausts at 117) the car made 300ish hp and 320ish tq. peak power was at 6100ish.
the only difference between the 2 dyno sessions was the cams being degreed. like i said, i will try to get graphs to get exact numbers and differences.

Originally Posted by tmhutch

The plenum floor angle should match the angle of the port opening. Flat is not bad but not the best.

Todd, do we agree on something?
The closer the floor is to the runners the more important that angle match becomes.

Originally Posted by uscstew

i was wrong on my peaks, but here is the graph

LTs and a ported intake will put that near the top of the bolt-on hp list

[hecdel40]

NA SVT you sound like a person with a lot of knowledge i own an 04 mach 1 with a vortech V2 supercharger and aftercooler I'm running a sct2600 maf with an IAT sensor. My question is can i use a blow-of-valve inted of a bypass valve.

Thank you,
Hector