ls vtec rs ratio really an issue?

[blackdahlia6]

looking at ls vtec theres really only a few things i can think of that are "bad" compared to normal vtec engines...
1. no oil squirters
2. no girdle
3. no balanced crank
4. lower RS ratio

but when looking ppl try to say yeah you cant rev to 8,000 on lsv because of the RS ratio. well wehn i look its 1.54 for ls block and 1.58 for c1 block. that doesnt seem like much of a big deal at all...i hear about ppl saying yeah the pistons will be pushed into the cyl wall and cause it to oval out, yeah that sounds realistic...sike...id assume that at most the rings would start to ware out no ovaling of the cyl wall, and id assume that would only happen after lots and lotsof revving well on over the 8000prm range.

id like some views on the ls vtec. as far as RS ratio

as far as just shot peen rods, new type r style pistons, rod bolts and new bearings what is the problem with revving to 8000rpm reliably? any input on this?

thank you

 

[Briansol]

i wouldn't take it to 9, but 8 is fine. It's the rod bolts you need to worry about more than anything.

 

[Taco15]

What you really need to consider is when your motor stops making power.
If your LSV is only making power to 7400 RPMS you're pretty much wasting time and abusing the engine even if it's built to withstand it.

And the power comes from the head. Its obviously common practice to upgrade rod bolts, and pumps. All builds are different.

 

[phunky.buddha]

The ratio itself isn't that big of a deal, just like you noticed. I spun mine up to 10k with the 1.54 ratio. It's all in how you build the bottom end.

 

[CAFROG]

It's the rod bolts you need to worry about more than anything.

Exactly. Worrying about the rod/stroke ratio is a waste of time b/c it will not be the first failing point. Upgrade the rod bolts and put new rod/crank bearings in.


Who ever was thinking r/s ratio.....seems odd. Unless they were ONLY talking about the clearance issues between the piston and the vavles but that would depend on the piston being used and the head gasket thickness.

 

[themanfrombeantown]

I'm a big believer in R/S ratio. That said, it will not be the direct cause of your engine blowing up. Most important are your rods and rod bolts, as these are loaded to the extreme with the high piston speed, which is directly related to R/S, higher R/S will lower the Vmax, but bulletproof rods/bolts can compensate for the high speed. A crank girdle is a good idea to prevent crank flex, b18cs have them. Improvements to valvetrain ensures the valves close fast enough to get out of the way and don't wear out. If you balance and strengthen everything with a proper build plan your engine will not fly apart. Now, if you want to put 100k on that engine taking it to 8k+ like most of us VTEC owners do on a regular basis that's where R/S may matter. When they say oval, they don't mean your cylinder bore will look like an egg, but no matter how well lubed there is wear and it is ever so slightly anisotropic due to directional loading, so it will oval over time and let oil by. Rings will probably wear quicker too due to high piston velocities as well. This just means you'll have to pull it, bore, hone, and re-ring. If you are building a motor that shouldn't be that big a deal to you. Higher R/S is better, there's a reason Honda builds most of their high reving engines with high R/S (CTR, Si, S2000), the exception being the b18Cs. But you can make 1.54 work if done right, just expect more down the road overhauling, LS-VTECs are not going to be set it and forget it 200k mile motors.

 

[blackdahlia6]

Thank u all for the input.

Im just concerned because I want to build an lsv, with valve job and pocket porting, I/h/e and a set of either skuk2 pro2's or toda b's. Im just concerned with those cams makinh power too high up for me to beat on it all the way up there in the power band AND have long term reliability....

Because if I cant rev consistently up high all the time to get the power theres no point in the lsv and ill just save longer for a gsr, ya hurd??

OPINIONS PLEASE

 

[blackdahlia6]

Thank you justin, thats wjat I was getting at...i want to at the least have a b18 with street esqe headwork I/h/e making 200whp being "set it and forget it", as far as bore and hone. I just want a build that gives me power yet peace of mind and I think getting me a gsr swap might get me that over the lsv...

 

[CAFROG]

Higher revs.....thats more of a top end issue.....valve springs and camshafts. The bottom end plays its role too but its more in terms of compression and bore...plus the aspect of bearing clearances, crank balance, and bolt tension strength.

 

[themanfrombeantown]

CAFROG is correct, as long as the bottom end is balanced and built right it's fine, more likely to break something in the valvetrain. My concern is I just don't see much data on longterm wear and reliability of this build, but I'm not an expert. You see the odd LS-VTEC blown up now and again on the forums, but that's probably due to a bad build. You just don't see a lot (any to my knowledge) of high reving motors with 1.54 R/S ratios from the manufacturer, there's probably a reason for that, I'm guessing longterm reliability and wear is it, 1.58 is already a bit extreme, 1.54 is a bit more even, and unless you have a really good builder I question one's ability to match Honda's factory engineering, testing and build you get with a B18C. I'm just saying unless you have a lot of confidence in the builder (yourself or a shop) this is probably not the path to OEM reliability. I'm not at all saying it can't be done, just from my experience the more skill required the more likely something will go wrong, it's an unknown, and therefore a risk that's all.