Finally decided to bite the bullet and build a 355 instead of messing with the LO3. Got a L31 at the local junkyard for $200 complete.

 

Ok lets see. So far the parts that I'm using in the build are as follows: GMPP 350 crankshaft, GMPP I-bean connecting rods, High flow oil pump, Silvolite short skirt flat top pistons 9.8:1 Comp ratio, Sealed power ch-series tri-metal copper-lead alloy rod and main bearings, Summit racing true roller time double roller kit, hydraulic roller lifters, self aligning 1.6 aluminum roller arms, comp hydraulic roller cam 230/236 duration @ .050 with 576/570 lift, L31 vortec heads, completely performance machined, cfm tech's 620 cfm TBI with an edelbrock performer TBI intake manifold, and Doug's 1 5/8 headers. Any recommendations on where to go from here would be great.

 

Read
http://members.uia.net/pkelley2/DynamicCR.html

long duration cams require more static compression
Would be worth doing a DCR calculation to see what it will be before you bolt every thing up
Download and install the DCR calculator at bottom of the page linked

 

Makes sense however since the motor is at the shop, I have no idea how to get some of these measurements. But the shop said after decking the block it will be more like 9.9:1.

 

I would suggest ALOT smaller cam... not so much because that's a "bad" cam or anything like that; but rather, because (a) that will require SO MUCH prep to the heads as to vault the $$$$ into aftermarket territory except that you'll still have just some stock heads, and (b) doesn't sound to me like you have much experience with tuning things like that.

I'd suggest picking a cam about 10° less .050" duration and about .060" less lift than that.

 

The head work is already done. He machined and ported the heck out of the heads and built them internally for this cam specifically. Total cost for assembly and all the machine work for this motor is $650 and he is going to put it on a running stand before I take possession. He also has a partner that will Dyno tune the car for $125 after I have it all assembled and installed.

 

Just got off the phone with the shop after getting all the measurements. Looks like the static compression ratio is going to be 9.94:1

 

Got any flow numbers ?
It is generally " not recommended " to extensively port Vortec heads because they flow so well stock and are respected for their excellent mid lift flow numbers

Comment condensed from a Kendricks test
"Two years ago we undertook an exhaustive study of the Vortec head in numerous modified states with different valve sizes, throat cuts, valve jobs, port mods, guide mods, etc. We used up about 10 heads, numerous valves, and about $50,000 worth of labor. The study generated 100+ pages of flow and swirl data.

Here is the short version. Out of the box, .480 valve lift, 350-400 HP dependant on the CR, cam, ring seal, oil control, blah, blah, blah.

Larger valves increase flow, chamber mods not needed, trade off between shrouded vs unshrouded valves not worth the decrease in laminar flow and swirl.
Throat cutting behind larger valves compliments the larger valves. Open the throat to the seat, remove the edge left by the cutter in the port.Blend the seats into the chamber, you don't want an edge here to disrupt flow and create turbulence.
"Bowl blend" and shortened guide in port also improves flow. Taper and blend the iron boss.

Minimal porting increases flow, too much increase in port size or loss of the shape of the stock port will decrease efficiency.
Unported, with all the other tricks in place, the Vortecs will flow about 235-240 CFM at .500 I and 165-170 cfm at .500 E, on a 4" bore at 28" .
With some careful porting there is another 5-10 CFM or so to be had.

But again the low lift numbers are unsurpassed at .100, .200, .300, etc. lift.
For example the Vortecs flow as much air at .400 as .500 and no 23 degree head that I'm aware of can match them at .200-.300 lift for the combination of flow and swirl.

Generally speaking, Vortec's stall at between .500 and .550 valve lift.
This is where flow actually begins to decrease. But their true strength is low lift flow which gives more area under the total flow curve.
And if you think about it how long are your valves at peak lift? They spend much more time at .400 and below, where the Vortecs outperform most other heads.
This combined with high velocity, lack of turbulence and superior combustion chamber design are where the Vortecs stand out.


Unported Vortecs with the "tricks" can produce 500 HP on well built, high CR, drag race short block.
425-450 HP is more realistic for a killer street engine running on pump gas."

 

I wish I had flow numbers but the motor isn't done yet. We didn't over port it though. We just port matched the intake and exhaust and then just cleaned everything up so that they are all smooth. I believe he said he was going to use 1.94/1.60 valves because I read that those heads don't really flow better with bigger valves. I'm pretty confident about the heads. But what I'm trying to figure out is what injectors to use. In my research I've read that a 50-60 lb/hr injector @30 psi should support 425+ HP

 

Another vote here for a smaller cam. The rest of your build does not support that 230 cam. It would be a dog down low, and will never get into its power range with your intake/TB.
Step down at least to the Comp XE 224/230 cam. If it were mine, I'd run something like the XE 218/224/110.
Don't chase a HP number; build it right to make the car quicker.

 

Dang. Wish I had posted before I bought the cam. It's already installed. Guess I'll have to run it and see what happens. Worse comes to worse if it really doesn't work, I can get a different one and sell this one.

 

Unless I missed something....That intake will not bolt to those heads. That cam is also going to be fun to tune with a standard GM ECM. It can be done, but definately not for the beginner.

 

I had the shop drill and tap the extra holes for the intake to mount to the heads and then he also port matched the two to make sure everything lines up. I know GMPP makes a TBI intake that will bolt right up to these heads but it was actually cheaper to have the shop make this one work then to buy the new one. Oh I've given up on even trying to tune this thing myself. Especially since he said he has a guy that will dyno tune it for me for $125.

 

Missed that
This GMPP version appears to be the only Vortec TBI intake available
http://www.jegs.com/p/Chevrolet-Perf...50534/10002/-1

be cheaper to by any 4bbl Vortec intake @ $200 (new )
http://www.summitracing.com/parts/edl-2116/overview/

and use a TBI adapter plate ($45)
http://www.summitracing.com/parts/trd-2211

 

The shop only charged me $100 in labor to make it work and he says that he has done it before.

 

Build it the way you want, it will work or it wont, I agree with otheres building it right the first time is better, this is how we learn, do what you can with what you want and go from there, if its not a DD, who cares, if you dont mind making changes thats cool, if you do, make the change now, Its your choice! Let us know how it works out for you.

 

With a 2.73 "one wheel peel" the cam discussion is almost irrelevant. Depending on your intended usage, some serious improvements are needed there.

I've run a 230/236 .520/.540 cam in a 355 a loved it. But I also had a manual trans and 4.11 gears with a 9" rear. Your car will run and drive ok, but it just won't be optimized without all the supporting mods. Big headers, deep gears, good stall converter, etc etc.

 

I agree the 3704 intake is going to be the part that chokes the engine the most. Almost like bolting stock exhaust manifolds on to the engine. That intake was designed to be run with a swirl port head 350 complete with a lame 194/214 performer cam.

 

Oh I will definitely will let y'all know how it works or not. I bought the parts after consulting with my engine guy who builds race engines for a living, so if it ends up needing different parts I don't mind changing them. That's what I got my workshop for. I enjoy turning wrenches.

 

I agree. I'm going to put a 10 bolt posi with a 3.73 gear with a TCI Break-A-Way stall and I should be good with the Doug headers. Don't want to go more then the 3.73's because I want to be able to drive it to work and back and its 36 miles one way on a 70mph road.

 

That's why I had the intake ported and I'm going to be using CFM Tech's TBI and spacer. I'm really looking forward to seeing how this works. If it turns out well, I will have ended up saving a boat load of money instead of buying a new intake and going to a 4 barrel TBI or EFI.

 

This is my biggest concern with the build in progress. I do not understand how he could have fixed this issue, without expensive TIG welding and CNC or hand port work.

 

Wow! I had no idea of that kind of difference. He was pretty confident that he could port match it. So I'm assuming that a CNC'd it. When it's all said and done ill pull it and take a picture. I'm really curious after seeing that picture.

 

The vortecs have a taller, raised port location than an old schoo cylinder head and most intakes do not have the "meat" necessary to cover the opening and even if they could, look at how much overlap there is in the ports.

 

The vortecs have a taller, raised port location than an old schoo cylinder head and most intakes do not have the "meat" necessary to cover the opening and even if they could, look at how much overlap there is in the ports.[/quote]

If he did "port match" it like he said, those walls would be paper thin. Guess I'll have to see what heck he did. Gotta admit I'm a little worried after seeing that pic.

 

If the stock intake does not work out for you. I love this intake with a TBI setup. I had the opening CNC machined for the larger ~2.00" 454 TBI bore and run a 3/8" thick TBI-2bbl carb adapter. Edelbrock makes a throttle cable bracket that works great and even accepted the stock cruise control cable with a small modification. The intake can also be drilled and tapped for NPT to hose barb fittings to install vacuum hoses such as power brakes and a PCV valve.

The one disadvantage is that it requires a taller cowl hood, UNLESS you mill the top integrated spacer down a good 1-2" and redrill and tap the carb stud holes. I had one milled, redrilled and retapped and ran it under the stock L82 aircleaner and hoodline of a 1980 Corvette.

I know it is alot of work, but with a milder cam than you run, I made peak HP at 6,300 rpm, shifted it at 6,500 on a 6,700 rpm rev-limit and had all the torque of a stock TBI engine.

 

If this setup doesn't work, I'll have to get another intake anyways. I'll try it. Although, I'm partial to my reverse cowl hood so i guess i would go the "mill the top integrated spacer down" route.

 

You can't port match a reg SBC intake to Vortec ports without adding ( welding ) material to the top of the ports on the intake
Look at the pic; there is a gap at the top that would only be sealed by a gasket with no clamping on it

The only way to get a "non Vortec SBC intake to work is to use one of the "raised port " single 4bbl hi-rise racing versions which would be a complete mismatch to the head anyway

 

Guess he is full of it when he said he could do it. I'll have to try and get a hold of him and ask him how he planned on doing this when it isn't possible. But that's why I am posting this project so I can get your opinions and take advantage of all of your collective expierence even though sometimes it's hard to stomach lol. I had no idea about the difference on these ports and I appreciate the heads up.

 

Are there any issues with the EGR on that 4bbl intake?

 

No, none at all; the passage in the heads that any EGR in any intake would connect to, are absent. So it can't cause any problems whatsoever.

 

Well I guess that answers my question even though I worded it poorly. Can the TBI work properly without the EGR hooked up?

 

I have these for sale..
https://www.thirdgen.org/forums/engi...rformance.html

 

The OP already has a set of Vortec heads
Why would he pay $1300 just to get a Vortec intake?

 

I agree with this link:

http://www.crankshaftcoalition.com/w..._compatibility

No one part standing alone makes a significant difference.Matched parts working together does.

What has been the history of Vortec's heads is the used market has a ton of cracked heads out there(thin castings) and need machining for valve springs.The as cast intake runners to suspend the A/F mixture is in no small part what makes them Vortecs.Porting on the exhaust port is the only real advantage.They are ok for 350's/355's,but once you go bigger the aftermarket supply has a much better answer.Well really the aftermarket heads as a general statement are much better for the 350's/355's over the Vortecs limitations.


We have done some do-overs for customers with Vortecs with aftermarket overheads and some swear we swapped the entire engine.When really all we did was match build the top haft given the bottom end.The sad truth is most people don't know what they are missing out with their combo.Truly the tune-up starts with the core build on out.

So the idea of go big or stay home with a cam without the supporting parts cast is a really bad answer.

 

Yeah I had to go through 6 pairs of cracked vortecs heads before I gave up and got a new set. Sure am glad I had all those heads manafluxed before we decided to use them. I also told the machinist not to go crazy with the porting. Just to port match everything and make sure there's nothing to hold up flow and we are only going with 1.94/1.60 valves. I finally decided to scrap the edelbrock performer idea and went with my builders recommendation and my fellow posters of going with a vortec carb intake and decided on the pro performance vortec hurricane intake maniford and just gonna put an adapter plate on top of it for the tbi since I don't have to worry about emissions.

 

As already said, big cam wont be fully utilized by intake and small tbi. Cam would be awesome in a mpfi single plane or vortec stealth ram efi or a carb build with little tighter lsa. It wants to turn rpm. Good for max effort drag goals but alittle hot for general street use

 

I agree but as I've already posted, the cam is already bought and payed for and installed and with the way the motor is being build, it will be a 6800rpm motor so I'm hoping it won't be too bad. At least I wont have too little cam LoL. Guess that's what I get for going solely off of the guys at Comp saying it was a good cam for my setup. But I know with the right setup the TBI I'm going to run will support up to 500HP.

 

That machine shop sure has some chap labor costs!
"Total cost for assembly and all the machine work for this motor is $650 "

 

I havent followed tbi too much but 500 hp thru an auto typically is 390-415 whp depending on your loss calcs. Have yet to see a tbi making those numbers. Also have yet to see stock vortecs make those numbers. Close one was a 383 making 481 at motor with mild cleaned up castings with good valve job. Smaller cam than yours but more lift. I am skeptical of tbi injection systems at those levels

Imo making 330-350 whp would be real good for stock vortecs

 

Yeah the guy is amazing! He's not the fastest but he does great work. Wish I had a pic of the finished bottom end. It's beautiful. The machine work is perfect and he cleaned up the exterior and painted it like a gloss black lacquer. Really sharp looking.

 

looking forward to some dyno numbers or timeslips.

 

On paper up to 500 with high end everything yeah but I don't expect that on my build. I'm really hope he can get those vortecs flowing as good as he claims. He says we should get a little over 400hp from this build and if that ends up being the case I will be very happy.

 

As soon as I get them I will be more then happy to post them. He has a partner that does dyno tuning so as soon as I have the car running I plan on taking to him to get those sheets.

 

Does he do computer tuning too? I would think that would be the key on a build like this.

 

According to my builder he does. Which I'm very grateful for. I have no false pretenses of being able to tune this thing myself.

 

Got pics of the finished bottom end.

 

I was there with a 9:1 350 and a milder cam and drivetrain that had worse losses than a F-car.

 

Where? 330's whp?

 

IS that a truck oil pan? Are you going to run a y pipe? If so it may not clear.