SBC Head to Block
:nono: So has anyone used vortex heads on a goodwrench crate 350?, Different intake,,,how about exhaust?
Cobalt327.I been setting here for abit trying to figure out how to be nice about my post.I have read some of your stuff and like it.
The O/P asked if anyone has used Vortec's.Well really had used them on a GM crate.Real street used them and not some idealized magazine article.Case in point is where in either ref's is the RPM where the hp or torque ratings reached??. Then with each step where is the consideration for if a T/C was needed to be purchased or a rear end gear change was suggested to enable anything to be applied to a normally driven street vehicle.End of the day it is at best bench racing value.Sure don't help much if your spinning it up the haft a dozen times a yr at 6,000 or 6.500 to get there.I know from working a dyno cell how you can control the environment to get results wanted and I know Ken D does as well.
I am not at the shop right now,but will check build sheets to see if we have ever done one like this before and did test and tune.Off hand I think I remember one that certainly didn't produce those kind of numbers and we have campaigned numerous 9.90 cars successfully for over thirty yrs.So I am very sure our tune would have found all there was if it was there.
Interesting they didn't degree the cam to straighten out GM's gear sets.
His vague question about Vortex heads:rolleyes: gets a vague answer. The first link is to show that, yes- there are crate 350s w/ Vortec heads out there. Makes 330 hp even w/a pos cam.
The second link shows that a GM crate engine equipped w/Vortec heads and some other mods made 402 hp and 416 lb-ft of torque. Totally realistic numbers. Seeing as how the article is a compendium of a BUNCH of tests that were done on the GM crate 350 SBC, if the OP has any desire to read more, he can easily do so.
AFA what gears or stall speed he needs- one vague question doesn't (for me) rise to the level of discussion of torque/hp peaks vs. torque converter stall and/or gear ratios. MUCH more info is required before any of that is even remotely relevant.
An interesting result showed up during the many dyno runs that was done w/the Goodwrench crate engine w/Vortec heads.
It has been often said that using an open spacer on the Edelbrock Performer RPM (not the Air Gap) will help the top end. The idea being that the open spacer would behave basically the same as the cut down plenum divider used on the RPM Air Gap.
Although a different cam might give different results, in this case the the power was down a LOT w/the 1" open spacer:
BTW the 'tame' test w/the Vortecs gave 384 at 5,700 and 401 lb-ft at 3,600.
Read more: GM 350 Crate Engine Build IV - Chevy High Performance
Chevy High Performance magazine did a build up several years ago where they took the bottom Goodwrench offering from GM, dyno testing it stock with a GM 4bbl aluminum intake and Q-Jet with iron manifolds on the exhaust. Then porting the original heads and replacing the exhaust manifolds with headers. Then boosted it with a Comp XE268 cam an Edlebrock Performer RPM intake with a 750 Holley they took this combo through the L98 'vette heads, the Vortec and on to TFS heads. Moving the peak horsepower from 230 something stock to around 420 with the TFS heads; all on the original bottom end of cast crank, GM P/M rods, and those homely round dish 4 valve relief pistons that General Motors loves so much. This story is available in a book with some other builds by CHP titled Small-Block Chevy Engine Buildups: How to Build Horsepower for Maximum Street and Racing Performance
Frankly, I like to start with me selecting parts rather than buying a crate motor and throwing half of it away as these bottom of the line crate motors like the Goodwrench above simply don't start from a good enough place where the component selection is optimized to get the most power for the fuel burned. With enough cam and race part fudging yes you can get a lot of power out of the Goodwrench, but it will burn gasoline like there's no tomorrow and you've taken the stock parts way into their ultimate load capability which substantially shortens their life.
GMPP offers some excellent crate choices that when compared to fixing the Goodwrench with Vortec heads are pretty cost effective. Examples:
10067353 the bottom choice 4 bolt main, 2 pc seal, mech fuel pump for 1700 to 2000 dollars to which would be added the cost of Vortec heads for another 600 or so dollars.
12499529 basically a cammed performance upgrade of the 353 makes 290 horses drinks a lot of fuel doing it because it lacks enough compression to optimize the cam it has. Costs 1900 to 2100 dollars includes 4 bolt mains, 2 pc seal, mech fuel pump.
12568759 this essentially is the late 1980s early 1990s L98 Corvette engine on a 2 bolt block, mechanical fuel pump, 1 piece rear seal costs run 2200 to 2500 dollars depending on where you shop.
12530282, L31L the light duty Vortec, used in half ton trucks. Features 2 bolt mains, electric fuel pump required 1 piece rear seal. Costs run from 2200 to 2400 dollars. Used in half ton trucks.
12530283, L31R the heavy duty Vortec used in 3/4 ton and up trucks. Features 4 bolt mains, electric fuel pump required, 1 piece rear seal. Costs run from 2200 to 2500 dollars. These frequently include forged crankshafts and the hard insert valve seat heads.
All of these engines use the crummy round dish, 4 valve relief piston and PM rods.
I prefer starting with a new or remachined block only because I don't like the budget end of crate engine offerings, especially their piston choice which is universally the round dish, 4 valve relief crown design. This has a large impact on power output, fuel burn efficiency, emissions, and octane requirements all of which are sub-optimized with this style piston. The biggest negative impact of this type piston is that the major distance from the cylinder head's squish/quench deck is too far. Where best performance is experienced around .040 inch (which is the addition of the deck clearance and head gasket thickness) the round dish piston can add another .040 to .100 inch to this distance which pretty much eliminates the squish/quench function. This causes the engine to have to be operated with richer mixtures than necessary and increases the octane requirement from the fuel. A flat top piston keeps a close distance between the piston and the head's squish/quench deck over all the available area, this reduces the fuel needed for maximum power output and lowers the engine's octane need from the fuel. You get more power, lower emissions and better fuel economy when this is done correctly. Now in the real world there is a limit as to how much compression any octane fuel can manage so often the compression needs to be kept around 9.5 with pump premium. A true flat top piston may not be able to achieve that when combined with a Vortec or Fast burn head, however, there is an effective alternative in the D dish, or sometimes called D cup piston. This design keeps the tightly closing flat surface under the heads squish/quench deck while controlling compression with a D shaped relief under the valve pocket. These pistons are a major improvement over the factory's use of circular dish pistons.
A rather common engine we build is similar to the CHP but starts with a new or reconditioned 2 or 4 bolt block. For street and claimer engines the SCAT 9000 Light weight cast crank is often used for builds up to about 420 hp or where rules required. I like to use the SCAT 4340 capscrew rod either 5.7 inch p/n 2-ICR5700 or 6 inch p/n 2-ICR6000 for 2.1 inch journals. These are also available for 2 inch rod journals. These are bushed for floating pins; I just don't build press pin motors.
The piston will have to be coordinated with the cam and the dimensions above but including the piston crown in order to drive out the best compression ratio for the engine. Taking some common places to start from as the engine I'm describing. The cylinder head having a chamber volume of 64 ccs, the gasket being a .019 inch thick shim style and the piston to deck having a clearance of .025 inch with a flat top piston with 7 ccs of valve relief the Static Compression Ratio (SCR) would be 9.9 to 1. Computing the stroke lost at the point in crankshaft degrees where the Comp XE 268 cam closes the intake valve which is 61 degrees after bottom dead center the effective stroke is 2.79 inches. This drives a Dynamic Compression Ratio (DCR) of 8.16 to 1. For a flat top or D dish piston working under a Vortec style combustion chamber this should be a 380 to 400 horsepower engine that will run on midgrade 89 octane, with the power peak under 6000 RPM.
Compression relative to the cam timing is very important. There are articles out there that proport to say that power gains through compression are minimal. These are written in a way that isnít explaining the story well enough for the casual reader and engine builder to really understand whatís being said. What they point out is that for a given and constantly held set of cam timing events, that when increases to compression are made beyond an optimum point the power gains are fairly minor as percentages. Whatís not being dealt with is the issue of having compression that is coordinated to the camís intake valve closing event. This is the concern of the Dynamic Compression Ratio (DCR) it computes the reduced working compression ratio based upon calculating how much stroke is used up before the intake valve is seated. At RPMs lower than the torque peak holding the intake valve off the seat results in reverse pumping of mixture back into the intake system. This makes the stroke look shorter than it mathematically measures which has the impact of reducing the compression ratio because the swept volume of the cylinder looks smaller when adjusted to the intake closing point. This is a very important consideration for any engine but especially a street driven performance engine where most of its daily operation will be at RPMs below the torque peak so the effects of reverse pumping are most profound. There are DCR calculators on the web a common one is found at Keith Black see >>> United Engine & Machine Co. Incorporated <<<.
So you can see for your money there are some choices that start out better than the basic Goodwrench and that there are considerations that when included to the engine design will greatly enhance its power output against the cost of fueling the thing while considerably extending the engine's useful life.
Do think in the big picture builds guys should build from the rear end forward matching everything up.Here I just said alot and you might want to give that some thought.
HP ratings at what RPM??.Wanta guess who gave Chevy the ratings yrs ago??.Yepper it was me.
Honestly I do not know why you seem to believe any of the numbers presented in the articles (that are the same numbers from the same articles cited by oldbogie in his post above, BTW) are "comic book bench racing":rolleyes:. What I DO know is I'm not going to waste any more time or bandwidth trying to convince you that the numbers there are real world. At least the OP seems to be satisfied, and in the end THAT is why I'm here.
mertolson, check your PM box.
The Vortec head has some limitations in their stock form. One of the biggest drawbacks is the limited amount of valve lift caused by the height of the valve stem guide boss. Anything over 0.420" lift needs to be checked closely for clearance between the retainer and valve stem seal. More info can be seen at the wiki page Valve train points to check.
There are several ways to address the limited available lift, from the cheap "ghetto grind" to the relatively expensive (but very effective) conversion to beehive valve springs and retainers along w/cutting the guide bosses down shorter and reducing their diameter to allow aftermarket valve stem seals.
The Vortec heads also require center bolt valve covers, a Vortec-specific intake, and either self aligning rocker arms or installing screw in rocker arm studs and guide plates to use non self aligning rockers.
The page Vortec L31 cylinder head has info you might find useful. This barely scratches the surface, so if you have any other questions please feel free to ask.
These are a good match for a 350/355 SBC.Chevy was pretty liberal in the term Vortec.You see these already have all the machine work done and a dual intake bolt pattern.185cc intake runner is just about right with that cc chamber it is a best buy.
Vortec Bowtie Cylinder Head Technical Notes:
• Cast-iron small runner or large runner cylinder heads*
• 66cc combustion chambers
• 0.450" deck thickness
• Hardened exhaust valve seats
• Machined for 2.000"/1.550" valves
• Maximum 0.530" valve lift (without modifications)
• Straight spark plug design
• No heat risers
• Drilled and tapped for 7/16"-14 screw-in studs
• Dual bolt patterns for Vortec and early style intake manifolds (early
model P/N 10051103; Vortec intakes P/N 12366573,12496820,
12496821, 12496822 or 12489371)
• Use intake gasket P/N 12529094 for Vortec intakes or dual pattern
intake gasket P/N 12497760 for early model intakes or Vortec design
• Dual bolt patterns for perimeter-style and center-bolt valve covers
• Vortec intake manifold three-step torque specs: 2 lb.-ft.; 9 lb.-ft.; 11 lb.-ft.
Small Port Vortec Bowtie Cylinder Head Assembly
• Completely assembled, ready to bolt on
• 185cc intake ports
• 65cc exhaust ports
• Use Fel-Proģ P/N 1470 exhaust ga
Dual pattern intake holes are not very useful. Because of the height of the Vortec intake port, only the single plane 'raised port' race intakes have enough height to actually mate to the Vortec port- but then they may be too wide or have other port fitment issues. The dual plane intakes that I know of do not have enough meat above the port to be ported to match the Vortec port, either, w/o having a vacuum leak or razor thin sealing surfaces above the ports.
As suggested two part numbers for intakes.The overall features make them best buy.
Funny you mentioned comic book bench racing earlier.
The Bow Tie Vortec heads are a good head. But as far as intakes go, the suggested early intake GM p/n 10051103 (shown below) is a raised port competition orientated single plane intake recommended to be used w/a 2" spacer. This style intake is not something you would ordinarily use on a street 350. And in that the OP originally asked about using the Vortec head on a GMPP crate engine having heads inferior to the Vortec heads (otherwise why swap them in the first place?), it can be safely surmised that he's interested in a street combo, IMO
As I indicated above, only raised port style intakes have a tall enough port to be used on a Vortec head. But just because the port is tall enough does not mean the intake will match up correctly to the Vortec intake ports w/o modification to the intake or head, or both. Nor does it mean the design is going to match up to a street application.
A much more suitable intake for a street 350 SBC w/Vortec heads would be the Edelbrock Performer p/n 2116 or the Performer RPM p/n 7116 for the Vortec. Cheaper, too. Even the GM p/n 12366573 would be better than the p/n 10051103, but the price is too high IMO.
Aaaaa yes we have used that intake on a street driven car.Responsive off idle threw-out the rpm range.You wouldn't think so,but cam selection does come into play as apart of the combo.Growth potential is built into it as well.
Cobalt-I consider you as a friend.Question is what have you done and not what you have read and believe.If it is what you have read,the O/P can do that himself.I am trying to get you to change for source of info to reading trade publications to become a life long student of the tech and applying that to your builds.Be able to read between the lines from sources that have a selling agenda.Become a expert in the tech of air/fuel dynamics,cam design,materials and how that impacts parts to name afew.
If you read Techinspector1's posts you see a guy who appreciates big picture builds.Considers that these engines are a system.Knows the tech and how it gets applied.
All these posts in the forums from O/P's involve more than the original question.It serves the O/P to bring those things to his attention because he didn't think of them or maybe didn't know.
|All times are GMT -6. The time now is 12:23 PM.|
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.