A little light on the lingo...cam gears
Oct 15, 2003, 02:28 PM
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A little light on the lingo...cam gears
I see that the only difference between Vishnu Stage 0 and 1 are cam gears. I know what cams are...is cam gears just a more specific term for a camshaft? Someone please help me out...
Also, the cost of either stage upgrade is relatively inexpensive...how much would the labor charge be for a new cam? Hopefully I'm asking the right question here...
Does anyone have experience with the Vishnu cam...is the compromise worth it (lumpiness at idle)? The power gain seems to be huge over the Xede and turbo-back exhaust alone.
Give me the straight story fellas...
Thanks!
Also, the cost of either stage upgrade is relatively inexpensive...how much would the labor charge be for a new cam? Hopefully I'm asking the right question here...
Does anyone have experience with the Vishnu cam...is the compromise worth it (lumpiness at idle)? The power gain seems to be huge over the Xede and turbo-back exhaust alone.
Give me the straight story fellas...
Thanks!
Oct 15, 2003, 02:46 PM
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No, the cam attaches to the cam gear. The cam gears are turned by the timing belt, which is turned by the crankshaft.
In the case of the Vishnu upgrade, and most references to "cam gears," they are actually referring to adjustable cam gears. Adjustable cam gears are two-piece designs where the inner portion that connects to the camshaft can be rotated while the outer portion remains stationary (or vice versa, it all depends on your frame of reference). This allows you to advance or retard the cam position relative to the crankshaft position.
There is a picture of the Vishnu adjustable cam gears here:
https://www.evolutionm.net/forums/sh...threadid=41760
Notice how the outer teeth are connected to the inner silver ring through those bolts/screws in the slots. By loosening the screws you can rotate the silver portion relative to the teeth. You can see the little tick mark on the silver portion under the degree indicator on the teeth. That indicates the advance/retard of the cam relative to the crankshaft.
In the case of the Vishnu upgrade, and most references to "cam gears," they are actually referring to adjustable cam gears. Adjustable cam gears are two-piece designs where the inner portion that connects to the camshaft can be rotated while the outer portion remains stationary (or vice versa, it all depends on your frame of reference). This allows you to advance or retard the cam position relative to the crankshaft position.
There is a picture of the Vishnu adjustable cam gears here:
https://www.evolutionm.net/forums/sh...threadid=41760
Notice how the outer teeth are connected to the inner silver ring through those bolts/screws in the slots. By loosening the screws you can rotate the silver portion relative to the teeth. You can see the little tick mark on the silver portion under the degree indicator on the teeth. That indicates the advance/retard of the cam relative to the crankshaft.
Oct 15, 2003, 03:42 PM
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The pretty purple / turquoise things on my engine are cam gears - they allow for minute adjustments to cam timing w/o removing the belt and resetting timing. Useless unless you're going to run really aggressive cams like JUN:
Oct 15, 2003, 04:51 PM
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Actually we have logged impressive gains with just the Vishnu Cam Gears on our Stage 1 kits. Around 6-8 wheel horsepower over a car without them, and even more at redline. Obviously with the addition of a good set of Cams the gains would improve even more. But to call the Cam Gears useless by themselves is doing them a diservice.
Brett Payne
Vishnu Performance.
Brett Payne
Vishnu Performance.
Last edited by DSMBRETT; Oct 15, 2003 at 05:01 PM.
Oct 15, 2003, 04:59 PM
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Originally posted by DSMBRETT
Actually we have logged impressive gains with just the Vishnu Cam Gears on our Stage 1 kits. Around 6-8 wheel horsepower over a car without them, and even more at redline. Obviously we the addition of a good set of Cams the gains would improve even more. But to call the Cam Gears useless by themselves is doing them a diservice.
Brett Payne
Vishnu Performance.
Actually we have logged impressive gains with just the Vishnu Cam Gears on our Stage 1 kits. Around 6-8 wheel horsepower over a car without them, and even more at redline. Obviously we the addition of a good set of Cams the gains would improve even more. But to call the Cam Gears useless by themselves is doing them a diservice.
Brett Payne
Vishnu Performance.
I don't think it's a diservice - I have an opinion about the mods I'm running, which is as legitimate as yours.
Oct 15, 2003, 11:57 PM
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The cams we provide with the Stage 1 kit come pre-indexed so there is no need for the user to fiddling with them on any dyno. The gains we have seen with them are quite substantial. Not only is peak power consistently improved, there is much less power roll-off above 6500rpm. Also notable is an improvement in knock resistance due to a reduction in exhaust gas reversion during the overlap period. The effects are similar to running a more aggressive camshaft without any drivability compromises. Installation costs is also pretty nominal (1-2 hours).
We stumbled upon this mod when trying to tune an especially knock-prone 100% stock EVO (which actually turned out be running on a bad tank of gas). With factory cam timing, the car couldn't make repeatable back-to-back dyno pulls due to knock activity. Once installing the cam gears and trying a whole mess of timing combinations, we found a setting that helped in many areas without hurting in any.
Just my 2c,
Shiv
We stumbled upon this mod when trying to tune an especially knock-prone 100% stock EVO (which actually turned out be running on a bad tank of gas). With factory cam timing, the car couldn't make repeatable back-to-back dyno pulls due to knock activity. Once installing the cam gears and trying a whole mess of timing combinations, we found a setting that helped in many areas without hurting in any.
Just my 2c,
Shiv
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Oct 16, 2003, 06:40 AM
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Yes there worth it!
I Have seen dyno sheets with and with out them. Top end power it extended after 6500 rpm. It's a hour job with the tool from
. I'm going to do this mod but waiting to see what cams Vishnu will be using for there stage 1 plus package. Maybe just doing them together to save time in the future.
Eric
Shiv post up my graph and Aldofo's to show eveyone the diffreance in top end power.
I Have seen dyno sheets with and with out them. Top end power it extended after 6500 rpm. It's a hour job with the tool from
. I'm going to do this mod but waiting to see what cams Vishnu will be using for there stage 1 plus package. Maybe just doing them together to save time in the future.Eric
Shiv post up my graph and Aldofo's to show eveyone the diffreance in top end power.
Oct 16, 2003, 08:16 AM
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Originally posted by AvatarOfWar
No offense, but I wouldn't bother with $300 and the job of swapping cam gears unless I was going with bigger cams. Tuning cam gears can also be very tricky for guys without dyno's in their backyard. 6-8hp hmm?
I don't think it's a diservice - I have an opinion about the mods I'm running, which is as legitimate as yours.
No offense, but I wouldn't bother with $300 and the job of swapping cam gears unless I was going with bigger cams. Tuning cam gears can also be very tricky for guys without dyno's in their backyard. 6-8hp hmm?
I don't think it's a diservice - I have an opinion about the mods I'm running, which is as legitimate as yours.
AvatarOfWar, what are you dyno'ing these days? I just did a search and couldn't find any dyno plots for your car.
Here is a picture of the Stage 1 cam gears:
Last edited by EVO Rosso; Oct 16, 2003 at 08:21 AM.
Oct 16, 2003, 01:02 PM
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Originally posted by EVO Rosso
Sorry but Brett and Shiv are being conservative. The cam gears were a huge difference on the dyno with stock cams and XEDE. High RPM HP was greatly improved on all Evos with the pre-set cam gears. This gives you some of the benefit of going with larger cams but with out the vacuum/idle problems. I do not disagree however, that you can make better top RPM gains with both larger cams and cam gears. By using just the cam gears you get a noticable top end punch without the drawbacks and cost of new cams.
AvatarOfWar, what are you dyno'ing these days? I just did a search and couldn't find any dyno plots for your car.
Sorry but Brett and Shiv are being conservative. The cam gears were a huge difference on the dyno with stock cams and XEDE. High RPM HP was greatly improved on all Evos with the pre-set cam gears. This gives you some of the benefit of going with larger cams but with out the vacuum/idle problems. I do not disagree however, that you can make better top RPM gains with both larger cams and cam gears. By using just the cam gears you get a noticable top end punch without the drawbacks and cost of new cams.
AvatarOfWar, what are you dyno'ing these days? I just did a search and couldn't find any dyno plots for your car.
The only dyno's nearby are 2WD, and I refuse to post a number run on one for my car. I don't drive or race 2WD, therefore the numbers aren't legit.
Oct 16, 2003, 01:17 PM
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Originally posted by AvatarOfWar
Well, don't ellude to big gains w/o numbers. Shiv's people say 6-8hp, what do you say? I have no vacuum/idle problems w/o any adjustments to my cam gears - and I've got 272's. I don't think you can compare using just cam gears on stock cams to the "top end punch" of bigger cams. If that were the case, everyone would be doing cam gears on street cars instead of cams. (i.e. "By using just the cam gears you get a noticable top end punch without the drawbacks and cost of new cams.").
Well, don't ellude to big gains w/o numbers. Shiv's people say 6-8hp, what do you say? I have no vacuum/idle problems w/o any adjustments to my cam gears - and I've got 272's. I don't think you can compare using just cam gears on stock cams to the "top end punch" of bigger cams. If that were the case, everyone would be doing cam gears on street cars instead of cams. (i.e. "By using just the cam gears you get a noticable top end punch without the drawbacks and cost of new cams.").
Oct 16, 2003, 01:47 PM
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Originally posted by shiv@vishnu
This is on our own shop car from several months ago before a few recent XEDE updates. But the effects of the cams (with custom tuning) is pretty obvious.
This is on our own shop car from several months ago before a few recent XEDE updates. But the effects of the cams (with custom tuning) is pretty obvious.
The effects of the "cams" or "cam gears"? I wouldn't debate the value of cams - I know they make power. It's why I run them - I'm arguing against spending on cam gears for stock cams. Show me where that makes signifigant gains in and of itself (not with changes to ignition timing and everything else, because then your results are muddled with gains from other mods).
Last edited by AvatarOfWar; Oct 16, 2003 at 01:50 PM.
Oct 16, 2003, 02:03 PM
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That dyno sheet shows the output difference with our set of Cam Gears installed running the stock cams with Stage 1. Shiv did tune the car for the cam gears which is to be expected.
Brett Payne
Vishnu Performance.
Brett Payne
Vishnu Performance.