Any of you guys use the 98 Cobra cams with a centri?

[SIZEMOREMK]

I've read some opposing things here on the usefulness of the 98 Cobra cams on centri blower cars...

I've seen dyno sheets and/or claims of 20-50 or more ft-lbs in the low-mid ranges with these cams (of course giving a little up in the high range). Which for my taste, would be preferable. I also read that advancing either the 96/98 or 03/04 intake cams by ~4-6* would help in the low-mid range.

I am curious how much of the impact may be due to the longer intake duration on the 98 cams vs the advancing of either intake cam?

One of the threads I read by "NA SVT" on another forum showed a before and after dyno sheet (in what I'm assuming was a N/A engine) with 98 Cobra cams at factory alignment vs advanced 6*; the low end seemed to jump up quite significantly in the low-mid range.

I cannot seem to find a dyno sheet that compares factory 03/04 cams to advanced 98 cams when used in a centri car; but there is a 10 page thread on another forum collecting centri setup details in which many of those cars claiming big numbers have the 98 cams...

I've read some things elsewhere on centri blower cams in general and seems like the leaning is more towards the exhaust duration being slightly longer than the intake duration; which does not quite jive with 204/196 on the 96/98 intake and 03/04 exhaust combo...

Cam selection, along with how a torque converter really works, has always been too much for me to pretend to understand... You talk to 3-4 cam grinders and all of em will give you a different opinion and some of those opinions would probably change depending on what mood they were in that day.

So assuming one was already planning to pull some things out of the engine bay, who would recommend swapping in 96/98 cams and degreeing/advancing the cams?

[massacre]

The 4v responds to changes in duration more than changes in lift. That is how well these heads flow. That is what makes the '96-'98 Cobra cams make their power.
Because of the quad cam design of the 4v heads, the intake centerline and exhaust centerline can be set independently of each other, thus changing the LSA.
This cannot be done with a 2v, to change the LSA 2 new cams must be ground.

Now on an NA application, advancing the ICL 4-6 degrees and retarding the ECL about the same amount can make some decent numbers.
For a boosted application, I think it's different. I don't think the boosted motors need as much duration as NA motors, and a Centri could be different even from that if I remember right. Blower cams usually have less overlap as too much overlap can hurt boost levels.

Degreeing cams is a no-brainer to me, you have to know where your cams are at, before you go advancing them. Otherwise you do not know what you are advancing them FROM lol.

[jnobles06]

centri's act more like turbo's so the faster you can spin the engine the more power it will make, not like a roots style where the boost comes on early in the rpm range. for a centri car, if i were using the 98' cobra cams, i would degree them to 0*. i have read articles where na 4.6l dohc's have picked up 20whp just from degreeing the stock cams alone because the banks were so far off from each other from the factory in some engines. if you read more about the 98 cam swap you will find that the na guys will not advance thier exhaust cam with the intake cam which helps increase cylinder pressure and thus power. in a blown car i would definitely advance the exhaust cam if i did the intake cams, but like i said earlier i would just install the 98 cams at 0* if it were my centri car.

[MOTOWN]

Centrifugal blowers and Turbos are not similar in the way they operate, spinning a centrifugal motor will not necessarily make more power like a turbo motor will which runs off of exhaust pressure, a centrifugal is dependent on the pulleys to make power.

[jnobles06]

no ****. i didn't say they were exactly identical. the faster you rev the engine the more the pulley spins. also the faster you spin the engine the more exhaust gas it makes. which is why centris and turbos make power in the upper rpm range and dont make boost at lower rpms. they don't hold as much air in the blower as a positive displacement blower and only have one impeller so it cant make power off the line as well as a positive displacement blower.

look at the compressor side of a turbo and a centri they look pretty close. the only difference is what spins the compressor.

[jnobles06]

and i never said a centri will make as much power as a turbo, just that their powerbands are more similar than compared to a positive displacement blower. turbos are more efficient because they use engine waste to create their power and dont consume power from the belt system like a centri.

[jnobles06]

see how similar they are compared to a PD blower?? not the same but similar. a bigger turbo would have made it look even more similar.

http://www.timskelton.com/lightning/race_prep/powertrain/images/eaton_v_kb_v_turbo_v_cent.jpg

turbo impeller
http://assets.bankspower.com/friday_inline_images/375/SEMA-2010_12lg.jpg

centri impeller
http://www.procharger.com/images/p1sc1_impeller.jpg

tell me again how the compressor side isn't similar??

[massacre]

centri's act more like turbo's so the faster you can spin the engine the more power it will make, not like a roots style where the boost comes on early in the rpm range. for a centri car, if i were using the 98' cobra cams, i would degree them to 0*. i have read articles where na 4.6l dohc's have picked up 20whp just from degreeing the stock cams alone because the banks were so far off from each other from the factory in some engines. if you read more about the 98 cam swap you will find that the na guys will not advance thier exhaust cam with the intake cam which helps increase cylinder pressure and thus power. in a blown car i would definitely advance the exhaust cam if i did the intake cams, but like i said earlier i would just install the 98 cams at 0* if it were my centri car.

By 0 you mean 114? :D
If you installed your cams at 0 you'd be needing 32 new valves lol

Believe me no need to explain cam timing to me, I have been degreeing cams forever and have '98 Cobra cams in my NA car.
We are saying the same thing, that is what I meant by "no overlap".

And we all know that PD and Centri blowers and turbos are different, no need to get too excited about that lol.

[MOTOWN]

no ****. i didn't say they were exactly identical. the faster you rev the engine the more the pulley spins. also the faster you spin the engine the more exhaust gas it makes. which is why centris and turbos make power in the upper rpm range and dont make boost at lower rpms. they don't hold as much air in the blower as a positive displacement blower and only have one impeller so it cant make power off the line as well as a positive displacement blower.

look at the compressor side of a turbo and a centri they look pretty close. the only difference is what spins the compressor.


Get your panties out of a bunch!:rolleyes: if your going to attempt to give blower 101 at least no what your talking about! a properly set up centri can make excellent power of idle , IF its setup right.


and i never said a centri will make as much power as a turbo, just that their powerbands are more similar than compared to a positive displacement blower. turbos are more efficient because they use engine waste to create their power and dont consume power from the belt system like a centri.

REALLY:confused: Dayuum the 100 year old mystery has been solved!:D

[ctrlraven]

Turbo = free power
Centi = rob peter to pay paul


Let na svt chime in on this if he chooses to, he is the cam guru.

[massacre]

Let na svt chime in on this if he chooses to, he is the cam guru.

To be honest, Todd is on to way bigger and better things now than '98 Cobra cams in '03-'04 heads, that is all old news by now lol.

[jnobles06]

By 0 you mean 114? :D
If you installed your cams at 0 you'd be needing 32 new valves lol

Believe me no need to explain cam timing to me, I have been degreeing cams forever and have '98 Cobra cams in my NA car.
We are saying the same thing, that is what I meant by "no overlap".

And we all know that PD and Centri blowers and turbos are different, no need to get too excited about that lol.


0* advance since i was talking about advance. i figured it was understood since i was replying to the op and he was referring to advance.

[jnobles06]

Get your panties out of a bunch!:rolleyes: if your going to attempt to give blower 101 at least no what your talking about! a properly set up centri can make excellent power of idle , IF its setup right.



REALLY:confused: Dayuum the 100 year old mystery has been solved!:D


no **** you are still missing the point.

i never said anything about the drive system being the same which is what your original comment suggested i was talking about


Centrifugal blowers and Turbos are not similar in the way they operate, spinning a centrifugal motor will not necessarily make more power like a turbo motor will which runs off of exhaust pressure, a centrifugal is dependent on the pulleys to make power.

DAYYUMM YOU SOLVED THE 100 YEAR MYSTERY FIRST!!! CONGRATS!!!

i was saying just that the power bands are similar. not the same or that they couldn't be modded. its called speaking in generalities.


centri's act more like turbo's so the faster you can spin the engine the more power it will make, not like a roots style where the boost comes on early in the rpm range.

so you might want to start reading slower and actually understanding what people are saying before commenting. and yes i know you can set up a centri with a blow off valve in the charge tube to get early boost but that's not how they are sold. most people would rather get a pd than a centri kit they would have to mod to get the same effect as a pd.

you didn't even offer the op any advice so what is the whole point your posts? to argue or look cool? damn you're such a bad ass. :bows:

[jnobles06]

:bows::bows::bows::bows::bows: :bows::bows::bows::bows::bows:

[massacre]

This thread had potential.

[SIZEMOREMK]

So after searching a good bit, not alot of specific detail on 4v centri cams...

The few generic centri cam articles I've found all say moderate duration for both, with slightly longer exhaust duration.

Also, all of the aftermarket 4v mild/street blower cam specs I have seen from the various cam manufacturers show an exhaust duration a little longer or equal to the exhaust.

There was a reference or two that said the slightly longer exhaust duration was to reduce pumping losses at higher RPM...

One particular cam, the crower stage 2 street blower cam, is awful close to the cobra cam 206/206 @.050 .475 lift (I'm sure its the same cam for intake and exhaust):
http://www.crower.com/camshafts/ford-4-6-5-4-4-valve-modular-camshaft-1999-up-set-2226.html

I am really curious why not use the 98 intake cams for the intake and the exhaust, assuming you could find them for a reasonable price. If planning to get the adjustable setup in order to degree the cams and advance the intake, would that provide any gains?

[Jeronimojc]

The Cobra 98 exhaust cams are the same as our exhaust cams so no need to change those.
98 intake cams on a centri set up is a good move in my book. I'll be doing the same, but I am also installing a stroker short block with 9.6:1 CR. I got degreeing advice from NA SVT for my particular application. Good guy.
Among other things, this mod gets you to higher RPMs. Thus you'll have more room to build boost and HP.



Sent from my iPhone using Tapatalk

[Jeronimojc]

Btw, here's what Todd recommended for my setup:

"I recommend installing the cams at 114/110. That leaves the exh cams in the stock position and advances the intakes 5 degrees."




Sent from my iPhone using Tapatalk

[na svt]

-A centri will ever make great power "off idle"

-Stock cams will never see a 20hp peak increase by degreeing.

- Turbo and centri powerbands have nothing in common as a turbo power curve more closely resembles that of a PD blower.

- "pulley'ing" a centri to provide "PD or turbo like" boost "off idle" will result in an overspeed condition by 5000rpm.

I would only run 96-98 cobra intake cams in a Marauder if they are advanced no less than 5 degrees for an FI combo or 8 degrees for n/a.

Crower stg 2 "blower" cams will offer only little over the 96-98 cams. The best cams for a PD blown marauder are those that have similar intake and exh durations and have 215-220 deg (dur). Longer dur cams will only hurt performance. Yes, people have made great power with longer duration cams, but some have also made big power and turned great times with stockers. The key is to maintain the intake valve closing pont of the stock cams while opening the valve much earlier. This will increase DCR and low to midrange power which is right where the marauder needs it as heavy, automatic trans vehicles do not benefit from making only big peak power.

[SIZEMOREMK]

What I was asking about was using all 4 98 intake cams. As in using the intake cams for the exhasut as well, or two left intake cams and two right intake cams.

The question is would 204/204 int/ex any benifit over 204/196 int/ex?

In either case, the intake would be advanced ~6 degrees and exhaust would be straigt up; or 108/114.

[na svt]

the stock exh lc is 110.

there is a small benefit to using the intake cams on the exhaust side but the cost to do is "big".

[RacerX]

This is an old setup I had. Stock vs. 98 Cobra intake cams (straight up, not advanced) and a NAZ PSRI. Low end dropped, but, power band was extended quite a bit. Reinstalled the long runner intake (after Todd's recommendation) and got my low end back without sacrificing top end gains. If I had advanced these, there would have been slightly better improvements.

http://www.mercurymarauder.net/gallery/data/579/Dynorun1.jpg

[SIZEMOREMK]

the stock exh lc is 110.

there is a small benefit to using the intake cams on the exhaust side but the cost to do is "big".

Man, I'm so confused...

Several places I have seen said that the LCs were 114 for intake and exhaust for both the the 03/04 and 96/98??

I seen your recommendation for installing these 108/110 and thought maybe that was advancing the intake 6* and exhaust 4*...

As for the big cost, what other than the cost of 2 more intake cams is required? Assuming adjustable cams gears and crank sprockets would be used already?

Or are you saying that the gains from using the intakes as exhasut cams would not be woth the cost of the 2 extra intake cams?

Thank ya sir! I appreciate the guidance!

[SIZEMOREMK]

Just to be clear here, what I'm after is not 1/4 times or peak HP, the interest is in more low-mid for better throttle response and seat of the pants gain when the mood strikes. I rarely get to the track, and when I do its only 1/8th mile.

In the past, I had a 3.8 V6 SC Thunderchicken that I did some pretty extensive work to, aftermarket upgraded eaton M90 @12+ psi, alky inj, cam, head work to include bigger valves and port work, and a AOD with wide ratio gearset, very mild non-locking converter, and stock 3.27 gears. This car had more down low and mid than my Marauder does and it was a V6; of course the Marauder makes alot more up top.

I bought my Marauder with the centri, not realizing how drastic the difference is between a centri and roots blowers; knew there would be a difference, but not so much. My prefrence if money were no object would be a twin-screw blower. That is not in the cards at this time, plus I'm not sure I would want to try a whipple or kenne bell on my bottom end (an MMR 600). I'm not interested in an eaton, I've had them and too much heat for daily driving. Next big project on down the road will be big block or whipple, might even be in a different car?

So without the PD option in the near term, I am trying to figure out how to get some more torque and better mid-range throttle response so I don't have to rev all the way up to get pushed back it the seat.

I would probably give up 20 or so peak HP for significant increase in area under the torque curve before 4500K RPM or so.

As for spinning the blower faster, I was thinking if could shape the power curve to hit harder eariler and peak closer to 5800ish RPM, I could pulley the blower as fast specs allow for a 5800Kish shift and call it a day, don't really care about the PSI. I imagine the PSI will drop a few lbs if the cams allow some more air in anyways.

So what I am after is info on whether these 98 cams in whatever combination would support such a goal.

Actually, this post by NA SVT on an other form shows the change in shape I am after, I'm curious how this would apply to a cenri car?
http://www.svtperformance.com/forums/showthread.php?905951-03-04-heads&p=12636362&viewfull=1#post12636362

Thanks guys!

[sailsmen]

From an old post;
"Timeslipe data from a Vortec and Trilogy. Same gears, tires, exhaust, TC, Eaton 12.5psi and Vortec 10psi. Can you pick which is which?

1.704 5.089 7.942 85.53 10.438 12.554 106.67
1.741 5.096 7.924 86.4 10.399 12.501 107.33
1.702 5.046 7.886 85.7 10.383 12.511 105.89
1.691 5.025 7.852 86.34 10.328 12.426 107.56
1.745 5.096 7.883 87.13 10.329 12.391 109.4
1.748 5.114 7.907 86.9 10.358 12.427 109.03
1.72 5.047 7.822 88.15 10.272 12.333 109.52
1.716 5.019 7.79 87.37 10.237 12.3 109.38
1.744 5.098 7.894 86.79 10.355 12.431 108.69
1.69 5.221 8.051 86.58 10.514 12.921 108.65
Stock Trilogy 388RWHP/369RWTQ

Stock + the Trilogy and + the Vortec both ran 12.9-13.3 depending on temps. As far as the Trilogy providing more low end Torque the 60' times show no descernable difference.

Can you tell which is which? The kits are so close in any given race it will come down to the driver every time.
I cannot tell which is my Cent and which is the Eaton. What this proves it that from a dead stop by the 60' there is no measurable difference. Maybe there is a difference for the first 20'?"

ps I owned a Thunderbird S/C, great car.

[RacerX]

Man, I'm so confused...

Several places I have seen said that the LCs were 114 for intake and exhaust for both the the 03/04 and 96/98??

I seen your recommendation for installing these 108/110 and thought maybe that was advancing the intake 6* and exhaust 4*...

As for the big cost, what other than the cost of 2 more intake cams is required? Assuming adjustable cams gears and crank sprockets would be used already?

Or are you saying that the gains from using the intakes as exhasut cams would not be woth the cost of the 2 extra intake cams?

Thank ya sir! I appreciate the guidance!

Being assembly line built, the exact lobe centers, separation angles etc. are going to be different on every single mod engine by X degrees. Even bank to bank. You can install the 98 intakes "straight up", without degreeing. This isn't the right way to do it if you want the full performance gain out of them. You need to get Cloyes adjustable cam gears and then degree everything. I doubt you can use intakes in place of the exhaust cams. I'm pretty sure that would cause major PTV issues. Not to mention, getting exhaust out of the cylinder isn't the issue. Filling the cylinder with more air and fuel is.

[SIZEMOREMK]

Being assembly line built, the exact lobe centers, separation angles etc. are going to be different on every single mod engine by X degrees. Even bank to bank. You can install the 98 intakes "straight up", without degreeing. This isn't the right way to do it if you want the full performance gain out of them. You need to get Cloyes adjustable cam gears and then degree everything. I doubt you can use intakes in place of the exhaust cams. I'm pretty sure that would cause major PTV issues. Not to mention, getting exhaust out of the cylinder isn't the issue. Filling the cylinder with more air and fuel is.

I do not see why the intake cams on the exhaust side would not work if properly degreed?

I'm not sure which adjustable cams to use, I've seen where the cloyes are popular, and the modular performance ones might also be gooduns?

If I end up messing with the cams, they will indeed get the appropriate adjustable gears/sprockets in order to degree and/or advance them properly.

It is my understanding that some cams had keyways and some didn't depending on year? I've not been in the 4.6 before, so I'm not sure of all of the details quite yet; I'm not sure if having the key will matter or not witht he adjustable gears and such.

But i do see where the crower cam above looks to be the same cams for intake/exh and both specs are pretty close to using two 98 cobra intakes.
Edited: I went ahead and called Crower, they did indicate that the intake and exhast cams were the same cams.