Since I'm bored...again, I thought I would post some comments on the ET heads I recently installed. I've got a 403 in my C6 that had a huge cam and MTI stage IIR heads. It felt really flat and I had this bizarre idea to try and increase velocity instead of increasing volume. To that end I went from a .248/.254 cam to a .236/.242 cam that I had ground for me and from the MTIs to ETP 215s. The 215s flowed slightly better than my huge MTIs telling me that not only was I getting slightly more air, it must be moving to do so with small runners.

The increase in power is phenominal. I'm not sure if the larger ETs would have done any better, but I'm happy enough to quit trying. I love these heads. TQ, is way, way up shredding tires through 3rd with the 3.42s and now through 4th with the 4.10s. I can roll into the throttle in 3rd and get all kinds of sideways. I know this is not productive to a good 1/4 time, I'm just making an indication of power statement.

What I really wanted to comment on was what was required to make the ETs work.
Longer Pushrods. Your particular applicaton will determine this, but they will have to be longer than stock. I checked mine and I needed 8.100, 8.125
Grind off a bit of the valve cover so the ALt fits. The heads are taller.
Take off the metal heat things on the spark plug wires. Don't fit in the holes. In fact the taller head really stretches the wires to an uncomfortable position. Next on my to get list is a set of longer wires.
Of course you need an adapter to make the stock rockers work.

Its a good looking head, well machined and pulls hard. I'm pretty happy.

 

I have the ETP 215's also and really like them.

 

hey, don't bogart the specs. on the heads.

chamber size, flow rates (intake/exhaust), etc.

what plugs you using ?

you're using the 'stock c6' rockers ? did you change out the lifters as well ?

 

The ETs don't come with a flow sheet so the best you get is what's posted on the website. They are cnc'd so I imagine they flow what they say all the time, evrytime. 66cc chambers and .045 Cometics put me at 11.88:1
Valve Lift Intake Exhaust Valve Lift
.100" 74 57 .100"
.200" 152 106 .200"
.300" 219 150 .300"
.400" 266 190 .400"
.500" 301 204 .500"
.550" 312 208 .550"
.600" 320 211 .600"
.650" 323 214 .650

I broke a lifter in my stock bottom end so I am very leary of lifters. I could not find anything that did not have failures associated with it. so, i just went with new GMs the first rebuild and kept them in this go round. When I beat the crap out of the car it gets noisy, and goes away. I'm thinking I may go with Morrels next go round. Lifters scare me. I'm running TR55s. I wanted to run Crane rockers but they won't fit, or I've been told they won't fit. I plan on replacing those if I can find something that works. Trying to get rid of as many weak links as I can. I'm still tuning, she is at 11.9 to ariund 12.2 WOT. There is still more left. I'm predicting a conservative 500/490.

 

Runner size going to etp225cc intake runners would have given more peak power at the expense of low end TQ. Intake runner size gets altered, not when you change displacement but rather when you change the operating speed of the engine. Since the stroker is staying the same on operating speed, intake runner stays the same for the same low end perfromance.

Andy at A&A reported no power gains with heads of 225cc and 240cc runners over the 215's. The 225's also have huge 2.08 intake valves and the etp's already have valve float issues with the 2.04. The springs need to be shimmed up replacements since the 977's show float at 6100-6300 on most set-ups that used them. The titanium intake valve option appears to be mandatory if you choose not to shim up or replace the stock 977's.

The etp's appear to be the head of choice until a possible 6 liter specific head appears from afr which is in the works. This new head has a reworked combustion chamber that is specific to the 4 inch bore. If there is a significant difference it may put the 205 that much higher on the power curve. The most interesting thing about both of these heads is the huge jump in TQ that is seen. H/C combos have been seen north of 460rwhp using tiny 224 cams but the truly amazing feat is how they destroy the tuner specific ported heads by 35 or more rwtq. I have seen recent tuner H/C combos' using everything but etp and afr heads since they make more money selling a head they ported in house instead of selling what is difficult to get and makes them little money. Bigger cams get ok peak HP but they dont get the peak 435+rwtq as seen with a good head. I have recently seen a H/C combo make almost 470rwhp and only 400 rwtq. At normal street speeds the car is only making 325-350 at 2500-3000rpm instead of the 400+rwtq of a etp at the same engine speeds. That is a sick difference. LS6 style ported heads are a dead technology. Off idle, the bigger TQ car would feel 10 times as strong with much more power under the curve.

The heads are difficult to get.

 

afr is world products ? isn't it ?

i had/have a set of world products torquer II heads on my '74 Camaro (360). very nice..and well worth the money.

67cc, 2.02/1.70, can't remember the runner sizes.

so how long till we see afr's offerings ?

i try to stay away from shims, i know, they're supposed to be safe and all, it's just something about them that makes me leary.

 

You cant just pop in spings at the 1.8 inches they come at. When you use high lift cams, valve float is controled by shimming springs close but safe from coil bind. They are the only way to adjust install heights. That is like saying, I dont like lug nuts.

They arent a 'supposed to be safe' issue. They are 100% safe and absolutely needed. I have never heard of a shim causing a problem. They are held in place by the 400lbs of pressure exerted by the sping and the valve guide keeps it from moving. It is no different from having a hardened seat as 99% of all springs come with.

You are beginning to confuse me.

 

i know, me too..

it's the 'concept' of 'shims' that makes me leary. i know they work and are perfectly safe (nothing to fail), they actually help make sure you get a constant compressed spring size, etc. if i had the choice between two identical heads but one didn't need shims i'd take the one that didn't. in my mind, it tells me the tolerances across the board are closer. that's all.

obtw: i don't particularly like lug nuts. the job they do is essential but dealing with them aint always a pleasent experience.

 

Mine aren't shimmed but could probably should be. I got a big ole cam and I think I need the extra help when I got the thing screaming.

 

prior to The ET heads; with a 224/228 cam my power levels were at 425rwhp/405rwtq. After the heads power jumped to 461rwhp/435rwtq.
That's 36rwhp/30rwtq with just the ET's. Yes you do need longer pushrods, and Andy had these spacers for the valve covers which worked well, and the plug wires fit OK. I'm glad I waited for the ET's, they were well worth it. I highly recomend them.

andreas g.

 

No, Dart heads are made by World Products. AFR heads are made by AFR (Air Flow Research).

 

thanks.

 

Jesel makes J2K rockers for ETP heads. Perfect fit.

 

They offer both a fully adj and a stock type don't they? I need to look into those.

 

I believe they only make the J2K for the ETP heads. But the rocker lines up perfect with the valve. You will have to mod the valve covers. Also if you use truck spark plug wires they fit much better than the stock set. I used a set of Taylor truck wires and the fit is perfect.


These are in my car not the wife's C6 I did notice they didn't take into consideration the additional deck height when they did the dipstick tube bolt so it's out of hole in the block slightly and would give a sightly false low reading. And it does take a while from ordering to delivery if you need a little non mainstream. I think it was just over 4 months till they were on my doorstep.

 

You keep refering to shims as if they are optional equipment or needed only for some particular head. Shims like lug nuts are needed in most applications. They arent needed by choosing one head over another. When you are dealing with a built motor that revs near the limits of the hydraulic lifters, you need to maximize spring pressures to retain valve control. Regardless of the head chosen you choose a sping and, depending on your choice of cam, you shim the spring up to near its max safe height from coil bind. It assures a minimum of spring resonance issues and valve float. Shims are required for proper set up of a chosen spring/cam combination. They arent dependant on head choice. The only other way to adjust spring install height is to get different offset retainers but they limnit the range of adjustment.

While choosing a spring that is overkill for your chosen cam works fine most of the time without shims, the best protection for the motor would be to maximize the open pressure for safety at high rpm's. Eventually springs weaken and would have benefited from it.

If you look at the dyno graphs of etp heads that use the weaker springs, there i s some odd power drop offs at some rpms. This is the exact situation that is avoided with shimming the proper spring.

 

What is most amazing about the ETPs are the mid-lift flow numbers. Over 300 at .500 lift. That combined with the small intake volume means serious velocity and therefore serious TQ gains. The AFR also makes great numbers given the small 205 volume.

 

Don't forget about the danger of running too much spring pressure... cam lobe surface damage.

There's a balance in there somewhere that a spring gives you plenty of high rpm control but isn't also isn't shimmed too much that it kills the cam lobe. Always consult an expert when choosing springs and shimming. What you don't know can and will cost you a lot of money if not correct!

Cam companies can tell you how much spring pressure their cam can handle.... its a cheap phone call to be sure.

 

Comp cams states that no spring pressure that works with a hydraulic lifter can damage a lobe on their cams. Solid roller motor use far more spring pressure and the same cam lobe density is used for that application. If you get valve float use a stronger spring. Going from a 125 seat pressure and 375 open to 135 and 425 isnt killing any lobe.

 

hence my question about lift at half.