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

S

SIZEMOREMK

Junior Member
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?
 
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.
 
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.
 
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.
 
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.
 
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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.
 
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jnobles06 said:
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.
Click to expand...

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.
 
jnobles06 said:
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.
Click to expand...


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.

jnobles06 said:
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.
Click to expand...

REALLY:confused: Dayuum the 100 year old mystery has been solved!:D
 
massacre said:
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.
Click to expand...


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.
 
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MOTOWN said:
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
Click to expand...


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

MOTOWN said:
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.
Click to expand...

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.

jnobles06 said:
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.
Click to expand...

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:
 
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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?
 
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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.



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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."




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-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.
 
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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.
 
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