I'm having a set of 243 heads hand ported, milled, and a valve job being done right now. They are reusing the factory 2.00 and 1.5 valves.

The heAds are off a C5 non ls6, so they should be the regular ls valves.

I'm wondering if it's worth a few hundred extra bucks to add 2.02 and 1.575 valves, while keeping the stock seats.

A knowledgeable person told me I would gain 5-1 hp and 10-15 lbs of torque by going to bigger valves. Others have told me not to even waste my time. This is an almost daily driver na car and I'm thinking the stock valves may be the best for reliability???

Could I get a few more opinions before I shell out the cash and upgrade? If it's really only a few horsepower and nothing I can feel, I won't waste my time.

Also, if I did upgrade, which valves are best? Manley? Ferrera?

 

Yeah I have a 228/232 cam with full bolt ons. Will 2.02 and 1.575 valves give a noticeable performance boost?

 

More air+More fuel=More power. Simply put. Probly wont be a huge gain tho.

 

The valve job is really going to make the difference. I would at least put in the larger intake valve. The LS1 bore isn't big enough to shroud a 2.02" valve.

 

Agreed. IMO, the increased low lift flow is worth it. An additional 1 cfm is worth up to 2.2 HP.

 

How many more cfm can you get by upgrading to a 2.02 valve?

 

I'm getting a valve job, along with porting and milling.

Does a valve job include resurfacing the original valves?

Is the porting usually done around the valves that are in there or can I just add some 2.02s?

I found a set of qualcast 2.02 valves on eBay. Are they junk? Is there a certain brand of valve I should get?

 

If your guy is just blending the button of valve seats in, then by adding larger valve you will lose flow or at best stay about the same, but if he is opening up the valve seats larger than what they are originally then a larger valve will gain you flow.. yes of course

Some people install the 2.0 valves in the smaller 1.89 heads with out opening the valve seat up, so actually they lose flow, but since most have their heads ported and what not at the same time they gain flow and are unable to even know that the larger valves are hurting the flow, all they know is they gained flow..

The correct way when installing larger valves is to open up the valve seat area.. one could even just open the valve seat up with out installing larger valve and gain flow ..

There is a diagram out there somewhere explaining this.. its all about how the air flows around the head of the valves and between the seat area.. even showing how installing the smaller 1.89 valve in a 2.0 valve seated head will gain flow ..

I only know this by what iv studied and it makes total sense.

neways hope this helps peace

Edit: Ok so this video will explain

 

Since they're cutting the valve job, have them cut it for the larger valve(s).

Normally, the cylinder head porter takes the valve size into consideration when porting a head. A good one does at least. When porting a head, the size of the valve basically sets how big the port can be as far as the Minimum Cross Sectional Area is concerned. This MCSA is often called the Venturi or throat, which is normally the area just above the seat in the port. It will generally be the limiting factor in how much air a port can flow.

A general rule of thumb is that the MCSA should be no more than about 90-92% of the valve diameter, so a larger valve will usually allow a larger Venturi. Since there are so many variables that come into play, it's hard for someone to really nail down a solid number for how much a 2.02" valve is worth, but 5-10cfm is probably pretty normal and anywhere from 5-20hp can be expected.

I usually use REV, Ferrea, and Manley valves. I think REV is the cheapest, but I haven't seen any issues with them. I probably like Ferrea the best out of the three though, but that's just my personal preference.

 

Good points. As the video showed, just grinding the seat for the bigger valve and dropping them in doesn't work. You need to enlarge the throat. The area just below the seat. And need to do it correctly so you can get an angle below the seat to transition into the throat.
A cutter could do all this in a single operation.

If you have noticed, just under the valve seat the stock heads have a radiused Venturi. It is the actual pressed in seat. And the material is very hard.

Just curious KCS, how much heavier are the aftermarket stainless valves?

Ron

 

Isn't it ok to upgrade to the 2.02 and 1.575 valves without changing the seats.

Then all they would need to do is blend in the bigger valves right?

 

Yes but you won't get the flow improvements you otherwise would

 

Damn. I wish I would have let Tsp cnc port and use 2.02 and 1.575 valves. They charge $950 for stage 2.5 porting.....plus state tax and shipping because I'm in Texas.

I paid $1200 for the hand porting, milling, and valve job. $1200+ seems to be the going rate around here for hand porting. I'm going to take pics and post on here when they're finished. I hope I get a decent horsepower increase out of them.

 

This is a little off topic....but I've found used vortech supercharger on Craig's list for $2500-$3000 range.

Would it be ok to add one to my current set up if I turned the boost down a bit?

Can I use the 228/232 cam and rebuilt stock bottom end? I would like to shoot for 600 rwhp.

 

If I was upgrading valves I'd get hollow intake as high rpm stability could gain you as much as any flow from a valve. If you have any kind of valve job, use a better quench gasket like a .040" and especially if you're getting the heads milled which I would do, measure for push rod length. Just the valve job can change it.

 

I've got a stock 2" valve weighing in at 100g and a Ferrea 2.02" at 109g.

 

Overlap and FI don't normally play well together. You CAN do what you want, but you would likely want a cam spec'ed for FI rather than a cam spec'ed for a nasty NA idle.

 

Here is the difference of flow with the tea stage 1 243 with stock valves and the tea stage 2 with 2.04 1.57 valves.

 

Those are some sweet gains int he 300-500 lift range

 

The gains are very good from the TEA 2.04"/1.575" package.
And a turned down LS3 (2.04") weighs roughly 86grams. The LS3 valves are typically less expensive than heavier aftermarket valve also.

They are what I run....

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