is upgraded timing belt necessary for 500+hp?

[stann999]

I am building my motor up with kiggly springs and a bunch of other mods and I'm just wondering is it really necessary for me to get a solid tensioner and a kevlar timing belt for my 500hp dd or am I ok with the stock setup? How prone to timing jump is the stock timing belt + tensioner setup?

 

[delta448]

Problems may occur quicker as a result of an increase in crankshaft acceleration rate. When you make big power, the timing belt sees more tension stress because the engine accelerates rpm speed quicker. At what point it fails will be different for differently tuned cars and differently mannered drivers. I know if I was spending the money to make 500whp, I'd certainly opt for the strongest T-belt I could find.

 

[gofer]

I am building my motor up with kiggly springs and a bunch of other mods and I'm just wondering is it really necessary for me to get a solid tensioner and a kevlar timing belt for my 500hp dd or am I ok with the stock setup? How prone to timing jump is the stock timing belt + tensioner setup?

My take on the upgraded timing belts is that its a big waste of your hard earned money. My motor skipped time about a year ago and I called a reputable DSM/Evo shop in Socal, Road Race Engineering to get my new timing parts. When I was rambling off the list of everything I wanted to replace in the mix I said "Greddy Timing Belt" and he stopped me in my tracks and what he said makes A LOT of since to me.

Greddy, Gates, HKS, etc. make stronger timing belts that advertise twice the life as a OEM Mitsu belt. The problem is that your OEM timing parts still need to be replaced every 60k and your probably just going to replace the belt along with it whether you dropped the extra $100 for a kevlar belt or not.

As for the tensioner I think sticking to Mitsu OEM is your best bet too. Who knows what kind of defects an aftermarket tensioner has?

Thats of course my opinion and what I was told by a very reputable DSM shop. I do agree that there are A LOT of threads on 4g's skipping time but I think it can be blamed on the installation.

 

[Calan]

I've always run and recommended OEM t-belt and components, but on this stroker I went with the Gates belt, just for a little added peace of mind. It's not so much about a belt failure... I just wanted as little stretch as possible.

Is it worth the cost? I dunno...but I feel better about it so it was worth it to me.

For everything else timing related you definitely want to go OEM only.

 

[Only2G4Me]

I agree with gofer, but I guess it's all about what give ya piece of mind. I will say however, to stick with the oem hydraulic tensioner. A solid tensioner is basically a block with a threaded rod through it. Since it's not self-adjusting like the hydraulic one, it will need constant check and/or adjustment. For a race car I suppose that would be fine. You said the car will be your dd tho, and who wants to pull the timing cover constantly to check the tensioner? I like working on my car but not that much .

 

[6boltpwr]

its all personal choice man. people are going to like different things from different expeirences. personally i have a kev belt for my car with the oem tensioner.

 

[gofer]

Its really just a matter of opinion and personal experience with the OEM belt vs the Kevlar belts. T-belts don't normally break whether its OEM or Kevlar, they typically jump time from improper tension on the belt itself (the install). In that sense it really doesn't matter whether the Kevlar belt is stronger or not, what matters is a proper install and tension on the belt is spot on. Kevlar belts will probably "stretch" less in the upper RPM range since they are stronger, however there is some debat on the consistency of how well those aftermarket (non Mitsu) timing belts are manufactured. If you've got a little extra money to burn and your trying to spend it on a Kevlar timing belt I say spend it elsewhere, like on the Jay Racing Timing Belt Tool Kit so you can install everything 110% correct. If you plan on upgrading your cam gears to something adjustable that are sweet anodized colors then get a Kevlar belt to match and a clear timing belt cover to show off what you got.

Buying that Kevlar belt might come down to piece of mind, knowing that your timing belt won't break bending your expensive valve train parts. But piece of mind for me is knowing that my OEM Mitsu belt was built within manufacturer specs and its got proper tension on it.

 

[stann999]

wow that really sums it up gofer

 

[dsm-onster]

If I put over $1000 porting, decking, new valve guides, new SS valves; I'd certainly mull over whether or not I should get a stronger belt that can tolerate higher stress moving through the rpm range.

On more than one ocassion, I've seen valves break off from jumped timing and take out the piston sending the rod through the block; the head in each instance was trashed too of course. I certainly understand why some would opt for a little more insurance, after installing $1200 worth of block upgrades plus doing $500 worth of machine work to it and then dropping a $1300 head on.

But with that said, frankly I've never seen a fresh stock timing set come apart even after lots of abuse on the setup.



I suggest a new stock tensioner over a solid tensioner for a frequent driver that wont be tore down after every season. Though you may even use a low stretch kevlar belt, you should keep an eye on the solid tensioner when the belt stretches EVEN A LITTLE, the solid piece is not self-adjusting.

 

[housegsx]

Why would there be higher stress on the belt from anything other than a cam/spring upgrade?

Also, I don't see how stretch is a concern when running a hydraulic tensioner.

 

[Calan]

Why would there be higher stress on the belt from anything other than a cam/spring upgrade?

Also, I don't see how stretch is a concern when running a hydraulic tensioner.

The hydraulic tensioner is meant to keep the belt tight over long duty cycles, mostly as the belt and other components wear over time. It's fairly low response time can't compensate for instantaneous stretch caused by more resistance in the valve train or faster acceleration forces. (This is just IMHO...I have no empirical data to back it up.)

I'm not jumping on the "must use Kevlar belts" bandwagon though. I still think OEM belts are fine; as stated earlier, I just decided to go with a little more peace of mind this time around.

 

[housegsx]

The hydraulic tensioner is meant to keep the belt tight over long duty cycles, mostly as the belt and other components wear over time. It's fairly low response time can't compensate for instantaneous stretch caused by more resistance in the valve train or faster acceleration forces.

Ok, that makes sense for the tensioner and a stronger belt for more resistance in the drivetrain, as I thought.
I don't think I buy into faster acceleration though. That would would mean I'd have problems with the belt system revving in neutral, although that's never a good idea to begin with.

I'm not jumping on the "must use Kevlar belts" bandwagon though. I still think OEM belts are fine; as stated earlier, I just decided to go with a little more peace of mind this time around.

That's what I'm thinking. I like going overkill on maintenance and reliablity.

 

[Calan]

I don't think I buy into faster acceleration though.

Well again this is just my opinion after mulling it over during my build, but here's what I was getting at...

With my 2.3L stroker and small turbo...the t-belt tension changes state much more rapidly than on a stock motor while under load. This should (in theory) translate to higher shock loads on the belt, which in turn would make any stretching issues that much more pronounced.

And while I'm thinking about it...

Why would there be higher stress on the belt from anything other than a cam/spring upgrade?

Another thing to consider is the effect of ACG's. Depending on the valve train geometry and how they are set up, you can have different amounts of resistance working on the belt at any given time due to the change in when the cam lobes are in contact with the valve springs vs. the stock gears. This would also put additional resistance into the valve train.

Just thought I'd toss that out there.

 

[99gst_racer]

On more than one ocassion, I've seen valves break off from jumped timing and take out the piston sending the rod through the block; the head in each instance was trashed too of course.

I'd be interested to know the cause of failure for ^^^ these guys. It seems to me that there's a higher probability for the auto-tensioner to wear out or compeltely fail or for the system to be improperly tensioned, over a belt stretching, separating, or otherwise underperforming and allowing cam timing to jump.

I've personally never used a reinforced timing belt before. Only OEM here. And I've never had a failure either. I would completely trust an OEM belt on a 500 HP engine, without a doubt.

 

[dsm-onster]

Oem belts "stretch, separate, or other wise underpeform". . . That is exactly why I wonder. But still I have an ol' black stock piece. I jsut feel antsy about the gamble now with my eagle wiseco combo with all the machine work costs; and including those that would install a ported head by someone like CB, I would flat out be fearful. Since. oem belts stretch/separate. Actually The tensioner couldhave very well been the culprit with either setup I saw/handled with this issue. Except the last setup, the tensioner ran fine afterwards, but only with a 14b setup revving to a stock redline because nothing else was left in it.

 

[Lavery]

I would say that gofer is right about OEM belts, Except the fact that his car wouldn't exactly be considered OEM anymore if hes making 500hp. I would say Def spring the cash for a low stretch Kevlar belt. At the very least it will give you peace of mind.

For a stock car i would go with a OEM replacement belt.

 

[9!'clipseDOHC]

For my build I went with a Gates Racing timing belt and everything else (tensioners, pulleys, bsek) OEM Mitsubishi.

I understand the point that RRE was making but I can see the other timing components lasting longer then 60k. Usually its the belt that gives out first and we just replace the other stuff while we're replacing the belt. For me having a stronger belt is a no brainer on a performance build.

That being said, just because the Gates belt is advertised to last 3x longer then the OEM don't expect to leave it on for 180k miles. I would still replace it at the OEM intervals, especially on a performance/racing engine.

For me its just like using synthetic oil which advertises that it only needs to be changed every 10k miles yet I still change it every 3k.

Just my opinions. Hope this helps!

 

[dsmtbopwr]

I have a greddy timing belt and the only reason im running it is because I got it for free. If i were to be doing a 500hp build id get a aftermarket belt...idk thats just me. It wouldnt hurt if youve got the extra cash.