I have wondered how these budget Edelbrock heads stacked up against my usual street budget performance upgrade head - the GT40P. A couple of days ago I picked up a pair of almost new 2.02" intake E-Streets. Here is a brief write-up of what I found.

On paper the E-Street heads should be a good upgrade - their flow figures show a potential of 490HP @ 500 thou lift. GT40P data from Stan Weiss site, ex Car Craft Magazine. This shows the E-Streets are 100HP ahead of the GT40P in flow potential.

Valve Lift .100" .200" .300" .400" .500" .600" .700"
E-Street Intake 65 121 174 216 242 249 -
GT40P Intake 58 121 159 186 190 195 -
E-Street Exhaust 42 92 130 150 162 168 -
GT40P Exhaust 45 88 112 125 127 128 -

The heads themselves look like Performer heads, except for the different engraving on the ends. The casting was of good quality, and the as-cast ports and chambers looked fine to use as-is.

The valves are stainless steel one piece items. The valve springs sit in spring cups. Locks & retainers are 7°. Guide plates and 3/8" studs are included. However the valve springs are tiny and weak. Only good for hydraulic flat tappet cams up to 550 thou lift. The Edelbrock web site specifically excludes hydraulic roller cams from use with these heads. A new set of higher performance springs will put this right. Being used heads I had already budgeted on replacing springs as part of a normal rebuild.

On disassembly and inspection I found where more money had been saved. The CNC machining at the manifold face and below the valve seat inserts was very poor. The inserts were up to a 1mm step from the machined casting. The intake ports weren't CNC'ed far enough into the ports which left a 3mm ridge on one port side, two other sides were half that and the last was almost right. Exhausts ports were OK though. I spent about 4 hours with a die grinder using a carbide cutter first, then a cartrige roll. Now they are a smooth transition like they should be.

One other thing I noticed about the heads by accident. The rocker arm stud holes are machined right through into 3/4 of the intake port (1/4 of the hole is blind). Edelbrock makes a point of saying they heli-coil these for added strength. But hidden under one stud was the broken-off piece of heli-coil used to screw it into the head. This was just waiting to fall into the intake runner, and then into the engine.

So, are they a good choice? I would only say maybe. If your application was a flat tappet engine used only for the street, they would be fine. But so would GT40P's. If your application was more powerful, figure on spending a day pulling them apart and tidying them up, then fitting a new set of valve springs. By then you may as well have bought a set of Performer/RPM's for not much more, and bolted them straight on. As for the flow figures above, with the valve-spring imposed performance limitations the full flow potential is unacheivable. I personally do not think these E-Street heads as-sold-new are any significant improvement over the GT40P heads (which are half the cost of the E-Street heads) in a budget street performance engine. However with a better set of valve springs and a port tidy-up they are most certainly a big step up from GT40P's.

Interesting write up. I've wondered whether there really is a place in the market for these entry level alloy heads that've been introduced to combat the cheap, Chinese rubbish that's been hitting the shelves. It seems to keep the price down, they're cutting corners themselves, which is neither beneficial to the customer or their brand name.

As you know, the GT40-Ps perform very well with the correctly matched parts and, in my opinion, there's not much point trying to squeeze anything in between them and a set of AFR 165s, Twisted Wedge 170s, or similar.

look for the datto ute (results 2 to 8 or so)
http://www.youtube.com/results?search_q ... rnout&aq=f


we built this motor dart block, 347w, untouched e-streets with lunati springs and lunati hyd roller, made around 400 at the wheels.

Were the lunati springs a drop-in replacement or did the spring seats need enlarging and spring cups and retainers replaced with bigger ones? What p/n were they?

I'm looking at a set of comp 941 springs that will drop-in at around NZ$230. This compares with a Performer RPM trade-up price of NZ$355 - hence why the E-streets don't really seem like wise buying to me. But if the Lunati springs are a better option I may go that way.

I'm also building a 347. Finished the short block a week ago, and these heads came up at just the right time, 10 minutes drive from home. The springs will take a couple of weeks to arrive from USA whichever way I go.

400rwhp is about 470fwhp (manual) or 500HP (auto) so the heads are definately living up to the flow figures once the valve springs are replaced. The combo you built must be very well optimised to get this close to the theoretical HP potential of the heads. 249cfm x 2.04 = 508HP at sea level.

they are k-motion springs (not lunati as i stated previously) were a direct fit, cant remember the spring part numbers but may be able to dig them out
cam was a lunati voodoo hydro roller, 750dp holley, weiand intake, was built specifically for burnouts therefore setup with clearances to suit

few more pics here

Thanks. I know the K-Motion drop-in option is a K-750. Ever so slightly higher spring rate than the comp spring but installs at 1.700" to get 130# on the seat, whereas the comp spring installs at the original Edelbrock installed height of 1.750" for the same 130# seat pressure - no shims required. The two springs are so similar I think the comp version has slightly more coils (maybe 1/10th of an extra coil) which would increase the seat pressure (or installed height) and decrease the overall rate. The difference in open pressure is only 10lbs @ 550 lift.

I am looking at a cam around 220-225 @ 050 to keep it streetable with EFI and a BTR auto, although I got a flywheel balanced up as well just in case it sees duty in a manual.

From the research I have done into these heads you are 100% correct in stating they exist only to compete against the Chinese imports... The castings are their Performer RPMs, but without any of the CNC finishing and the spring/retainer package is really only good for very mild hydraulic flat tappet cams.

Personally I would rather spend a few hundred more initially & get a much better product you can bolt straight on ie TFS Twisted Wedge 170cc.