Hey guys,

I recently picked up a Camaro RS with the L03 305 engine. The car is mostly stock except for headers, Edelbrock TBI manifold, and an open element air cleaner. I started doing some reading on-line for performance options and I was thinking about putting some Vortec heads on it. Chevy High Performance has a great article on a Ported Vortec (L03) 305 running TBI that put out 257.06 rwhp at 5,150 rpm, 294.96 rwlb-ft at 3,500 rpm. The specs for the engine can be found here.

This got me thinking…Vortecs are great performing heads, no doubt, but I wondered it there was a better choice out there particularly because I have some performance parts already. When you consider that Vortec heads require machining for high lift cams, new valve springs, and maybe some porting to improve things a little, it doesn’t seem like a very inexpensive/easy swap anymore. Furthermore, I’d have to change to the pricey GM Vortec TBI intake manifold and if I want to retain EGR, I’d need Vortec/EGR-compatible headers or use the Edelbrock EGR kit #2899. Unfortunately (or fortunately depending on how you look at it), I have ceramic coated headers and I don’t want to mare them up!!

I looked into the Edelbrock centerbolt Performers, but they don’t flow as well as I’d like (229 cfm/166 cfm at 0.500”) and they’re $1200. Vortecs flow 239 cfm/147 cfm at 0.500”. So I’d have to get the Vortecs ported if I want to make the same power numbers as the CHP 305 build-up. I searched around and I think I’ve found the perfect head – Trick Flow’s new 175cc SBC head!! This head has several key advantages:

1. a direct bolt-on replacement head (centerbolt style head),
2. it’s aluminum so it would be fairly easy to clean up the ports – a DIYer job,
3. they flow better than Edelbrock’s or Vortec’s (242 cfm/172 cfm at 0.500” lift),
4. 56cc combustion chamber – rock on!!,
5. they come with several valve spring options, up to 0.600" lift, and finally
6. despite the initial cost of the heads, it would be cheaper for me to bolt these on than run ported Vortec heads, plus the added expenses that I mentioned earlier.

I think with a little light clean-up, you can achieve 250-255 cfm/ 180-185 cfm at 0.500” lift. I’ll also need a custom chip, but I’d need that with the Vortecs anyway. That and a new roller high lift camshaft and a higher stall converter.

Just for kicks, I decided to enter the exact specs of the CHP 305 build-up into Desktop Dyno and see what it gets, except using the Trick Flow heads (head flow data is on their website BTW). 56cc chambers with a thinner 0.039” head gasket will give a 9.5:1 compression ratio instead of the 9.8:1 in the CHP article (they shaved the Vortec heads to 53cc – again more expenses!!). Want to know how it’ll perform? How ‘bout 340 hp at 5000 RPM; 370 ft-lbs at 4000 RPM. Assuming a 22% drivetrain loss, that’s 265.2 rwhp and 288.6 rwft-lbs. Probably a little bit high, but these dyno simulations can be fairly accurate. Best part is that Trick Flow bare castings start at $798, or $1000 for the entry level heads depending on the spring options. Pricing is from Summitracing.com. I think this is an amazing deal!! I’ve included a pic of the “dyno run” below. Just thought others might be in the same position as me with some performance parts already on their engine, but also looking for more power. From what I've read, the L03 heads are like breathing through a straw. I hope this helps some – and provides some different head options that I don’t think have been discussed at any length here. Now discuss...Take care!!

Red

 

Where are you getting the flow numbers for those heads? I looked at their site and didn't see any.

Also, there's a lot more to a head than the .500 flow numbers. For a street engine, the mid flow numbers are much more important. What a head flows at .300-.400 lift makes all the difference in the world.

The site says the heads are designed for 265-305 engines, so I'm assuming the combustion chambers will be designed for small bore cylinders. If so, they should be more efficient than putting a head designed for a 350 + on a 305. As far as I know, this is the only aftermarket head (with the exception of the S/R Torquer 305) designed as a direct fit for our engines. The fitment chart, however, lists applications for up to 400 c.i., so I'm not sure.

If they are sized for small bores, that also poses a problem. Vortecs, Edelbrock ETecs, etc., will easily swap over to a 350/383, if the combustion chambers on these heads are truly sized for a small bore, they shouldn't work nearly as well on a larger bore small block. With 350s so cheap, it makes a lot more sense to swap over to one when the 305 gives up the ghost than it does to put money into the 305 short block, so dropping nearly 1200.00 on a set of heads that won't perform to their max potential on a 350 or bigger might not be the best way to go; it limits your choices.

I also think those hp numbers you got might be a little high. My Desktop Dyno doesn't show TBI as an induction choice. Is there a newer version that does?


http://www.trickflow.com/product/che...3degree175.asp

http://store.summitracing.com/defaul....asp&x=25&y=10

 

http://www.trickflow.com/product/che...75_airflow.asp

I didn't say that these heads should be used on a 350! If I were using Trick Flows on a 350 or greater displacement, I'd go with their 195 intake runner head, 62cc combustion chamber. Flow specs are even better and they have CNC versions available:http://www.trickflow.com/product/che...ee_airflow.asp. The 175cc TFs are designed for 305 and smaller SBCs.

Red

 

Here are the comparisons of the flow data for the Vortec and TrickFlow heads

Vortecs
PORT SIZE: 170cc
CHAMBER: 64cc
VALVE SIZE: 1.94 / 1.5
FLOW@.100: 70 / 48
FLOW@.200: 139 / 101
FLOW@.300: 190 / 129
FLOW@.400: 227 / 140
FLOW@.500: 239 / 147
FLOW@.600: 229 / 151

Trick Flow 175cc
PORT SIZE: 175cc
CHAMBER: 56cc
VALVE SIZE: 1.94 / 1.5
FLOW@.100: 61 / 53
FLOW@.200: 127 / 105
FLOW@.300: 180 / 142
FLOW@.400: 216 / 160
FLOW@.500: 242 / 172
FLOW@.600: 242 / 180

Trick Flow 195cc (non-CNC)
PORT SIZE: 195cc
CHAMBER: 62cc
VALVE SIZE: 2.02 / 1.6
FLOW@.100: 51 / 58
FLOW@.200: 136 / 98
FLOW@.300: 191 / 136
FLOW@.400: 230 / 163
FLOW@.500: 253 / 177
FLOW@.600: 254 / 190

Trick Flow 195cc (CNC)
PORT SIZE: 195cc
CHAMBER: 64cc
VALVE SIZE: 2.02 / 1.6
FLOW@.100: 56 / 56
FLOW@.200: 138 / 105
FLOW@.300: 198 / 146
FLOW@.400: 237 / 171
FLOW@.500: 257 / 186
FLOW@.600: 258 / 196

Again, these are direct, bolt-on centerbolt heads.

Red

 

As far as TBI modelling on Desktop Dyno, Dyno Don here and others have done TB flow tests at 1.5"Hg and came up with 490-520 cfm. TurboCity or other similarly larger 46mm TB's flow about 590-620 cfm including the "ultimate TBI mods". These are the numbers (plus dual plane intake) required for Desktop Dyno. BTW, DynoSim is more accurate when modelling roller camshafts because it is able to use both 0.050" and 0.001" specs simultaneously for a better simulation. Estimating roller camshaft set-ups in DD2000 is difficult.

Red

 

That's not necessarily the case. For example, in November 2004, Super Chevy tested Edelbrock's ETec 200 heads on Danger Mouse. The next month, they swapped to ETec 170s and made more HP and Torque throughout the entire rpm band; including peak numbers, and that's with a .574/.584 lift, .234/.238 duration @ .050 camshaft. They declared the ETec 170s the best heads, by far, that they ever tested on the combination. Even though they would later make bigger numbers with Dart heads, they concluded that combination would not be streetable, while the ETec 170s would.

The smaller runners promote velocity, which is where heads like Vortecs and Fast Burns make a lot of their power.

Also, looking at the trick flow heads' flow chart, they make the head in both a small bore and a large bore combustion chamber. If I was going to get them, I think I'd get the larger bore chamber. Whatever losses I experienced due to the mismatch would be offset (for me) by the ability to use the heads on a 350 or larger.

 

I think you're missing the point of why I originally submitted this thread - E-tec 170's or 200's are Vortec-style heads and they are not direct bolt-on's for TBI (or TPI) engines. You would have the same problems as if you were swapping the L03 heads for Vortec heads (or any other Vortec-style head for that matter). Maybe a better comparison would be head swaps that are only the non-Vortec, centerbolt style. I think these Trick Flow heads are an excellent option for a 305 or 350 who also have some performance upgrades already on their rides where swapping these heads will be cheaper than if they were to do a Vortec swap with all the hidden extra expenses. Don't shoot the messenger here. Try and name one other non-Vortec-style, centerbolt head out there that has similar flow data (without porting) to the Trick Flows and has the smaller 175cc intake runners and 56-58cc combustion chambers, designed to work on a 305. I don't think there is one and I've looked at a lot of possibilities.

I'd like to read that article you've mentioned because I would have expected the result to be the other way around. Another factor is matching the other performance components to your heads. I'm sure with the right engine combination, the E-tec 200 will outperform its smaller counterpart.

Red

 

So, you're going to swap those trick flow heads onto your car and keep the stock intake? Obviously not, and, since you're going to swap intakes when you swap the heads, it makes no difference whether you go with a vortec-style head or not.

The point I was making was not that you should choose ETecs over Trick Flows, anyway. It was that larger runners don't necessarily make more power as displacement increases. Higher velocity improves combustion efficiency.

If you want to read the article(s), you're going to have to find the November and December 2004 issues of Super Chevy, the articles aren't posted on their website. As far as parts mismatch, and you're being sure the 200s would outperform the 170s, that puzzles me. The whole concept behind Danger Mouse was to systematically test numerous combinations of parts on the same short block, so accurate comparisons could be made. What parts might be mismatched? More cam? How much more lift than .575/.585 do you need? If you read the articles, they actually thought that cam would be too big for the 170s, and were suprised to find it wasn't. More carb? If the wideband 02 says you're at optimal A/F, I'd think you're ok there. When, after more than 2 1/2 years of testing (including Trick Flow, AFR, Dart, and numerous other heads), they declare the ETec 170s the best heads they've tested, I think I'll take their word for it. 485 hp and 475 lbs. ft. torque is pretty convincing to me.

I spoke to Edelbrock several months ago about which heads they'd recommend for a 383, they said they'd been just as suprised with the Danger Mouse tests as the guys at Super Chevy. In their own dyno testing afterwards, they said the 170s were better on a street 383 with cams under .600 lift, but the 200s did better with cams over .600 lift, although only in peak hp. Everywhere else, the 170s were better on a 383. Edelbrock's position is you don't see a real difference until you get into a 400 or larger.

 

Good info to know - Thanks. Like I said, I'm surprised. I guess the higher lift over 0.600" technically proves my point though - it's all in the combination. But I agree, the E-tec 170's would make a better street head.

Also, I don't have the stock intake manifold on my ride - I already have the Edelbrock unit. That was covered in the first paragraph of my first post. The Vortec TBI manifold is also $310 and harder to find on ebay. I just saved $310 right there. The Edelbrock TBI unit is much more common and can also easily be found on ebay for much less if needed by those who don't already have one. Here's one for $127 right now on e-bay - http://cgi.ebay.com/ebaymotors/EDELB...spagenameZWDVW

 

I missed that. One thing to consider, though, is that the Edelbrock TBI intake might not work well in a high hp situation. The consensus among many on here is that a carb intake flows better. It'd be a shame to spend all that money on great flowing heads only to have it bottlenecked by a poor flowing intake. I'm only aware of one actual dyno test on a Performer TBI and a carb intake. They cover the comparison in the second article:

http://members.tripod.com/GRK_Taz/tech/camaro.pdf


http://members.tripod.com/GRK_Taz/tech/camaro2.pdf

The intake they tested was a standard Edelbrock Performer, which worked better than the Performer TBI. There were a number of people on here who had great results with the Weiand 7525, and the Edelbrock Performer RPM Air Gap is miles above the standard Performer in carbed applications; I'd assume it would be better in a TBI app. as well

 

The edelbrock 3704 works just fine in a High HP TBI application, especially if you can get away with boring it to 2" and use a 454 TBI. The other option that already comes with 2" bores is the cheaper Holley Projection intake for 1987-1995.

 

Which intake is better overall, the Holley unit or the Edelbrock?

 

So which intake do you guys say is better overall, the Edelbrock or the Holley?

 

The Edelbrock is a direct bolt-on, gives more low-mid range torque, better fuel mileage, and won't foul up inspections. Paint it semi-gloss black and 95% of the world would never know the difference.

The Holley takes some work to bolt-on, gives more upper RPM performance (when combined with a 454 TBI unit), uses substantially more fuel, still uses EGR, but looks totally different than a stock TBI intake. Holley has a disclaimer that it is not intended as a stock replacement for 1987-1995 TBI engines.

They both have their advantages and disadvantages. In my application, I decided to run an Edelbrock with a TD Open TBI spacer on top, and a stock SBC TBI.