NSW Corvettes
Technical Tips => Engines - Carbies - Exhausts - Dissys => Topic started by: Ray45 on March 25, 2005, 12:31:39 PM
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Need your opinions on this upgrade......Have a 79 L48 350ci for which I have just purchased vortec heads, inlet manifold and camshaft from a 330hp Suburban Imports crate motor, which had only done 1500 ks. I intend to put a 750cfm Holley on top. Already have headers on engine.
Any thoughts on HP output or any directions on this upgrade would be appreciated.
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Bore & Stroke to a 427 mighty mouse!!!!!! YEEEEEEEHAAAAAAAAA
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What are the flow figures for the Vortec heads and also the camshaft specs?
You may also find that the 750cfm Holley is a little more than you need for that engine as is.
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Originally posted by Brutus
What are the flow figures for the Vortec heads and also the camshaft specs?
You may also find that the 750cfm Holley is a little more than you need for that engine as is.
Agree with Brutus. Unless your beast is doing some serious RPM's a 650 should be fine.
My beast is reving to 6200 rpm, roller rockers, cam, etc with 355ci and the holly 650 double pumper, competition style, is fine. Bigger is not always better
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Bigger is not always better [/quote]
YES IT IS!!!!!!!!!!!!!..............SPEAK FOR YOURSELF
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Originally posted by 69 DIRTY RAT
Bigger is not always better
YES IT IS!!!!!!!!!!!!!..............SPEAK FOR YOURSELF [/quote]
We shall see.
Any updates on when your project will be on the road?
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Originally posted by 69 DIRTY RAT
Bore & Stroke to a 427 mighty mouse!!!!!! YEEEEEEEHAAAAAAAAA
For what its worth you can't quite go that far with a stock 350 block.
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Really? I've heard of SB 427's...
If you cant use the 350 block, what do you have to do?
I see a mighty mouse in my future...;28
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I hear you Adam. ;-)
From what I understand 420ci is about as far as you can take a regular 350 block. Cost is more than most strokers (like 383's) due to the machining needed to clearance the rotating assembly in the block (and the rotating assembly needed to make this combo possible).
If you use a regular GM 400 block (still a small block) you can go to 427ci.
If you use an aftermarket block, depending on what type of block you can go as high as 472ci from what I understand.
(I have been told that the C5R blocks can be taken out as far as 491ci!).
As usual, it all comes down to how much you want to spend.
Sorry Ray45 - didn't mean to hijack your thread.
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Damn,:b4
And it sounds like these 400 blocks are gonna be rarer than big blocks.
I originally wanted to just get a used SB for cheap- and work on it and eventually put it in.
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No mate they aren't as common as 350 blocks but they aren't rare. Last time I talked to someone about them $500-$1000 would get you a sound donor block to start with.
Not all 400 blocks are the same so you need to do your homework before you buy one based on your plans for the motor.
Having said all that a strong 350-383 is more than you can use on the street and should get you into the 12's anyway while being reasonably affordable compared to the larger cubed motors I have referred to above. I wouldn't go any further than 383 in a small block unless you wanted to run some really impressive numbers at the track.
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To actually answer the original question...... an L48 with mild cam, auto, 3.08 diff, re jetted Quadrajet, Edelbrock intake, stock heads, port matched intake with 2.02/1.6 valves, dual exhaust (no cats), recurved dizzy will take you in the vicinity of 220 RWHP.
A 750 is too big! You need to work out your airflow when choosing a carby. You'll find all you're drawing is 450-500cfm @ 5500rpm anyway.
Cheers
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WHITE RIDER I think you just need to get my big block! you can bore/stroke to 540ci (max with standard block!). Put a 950 or 1100 cfm carby on it then your laughin! Pure wastage overpower!
YEEEEEEEEEEEEEEEEHAAAAAAAAAAAAAAAAAA
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haha, this from a man whos idea of car "handling" is going around in circles!;35
Actually, boring out an engine should LIGHTEN it right?;27
Well, the '80 diff should be good for 400hp.
Will the BB bolt straight onto a TH350?
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Originally posted by Ray45
Need your opinions on this upgrade......Have a 79 L48 350ci for which I have just purchased vortec heads, inlet manifold and camshaft from a 330hp Suburban Imports crate motor, which had only done 1500 ks. I intend to put a 750cfm Holley on top. Already have headers on engine.
Any thoughts on HP output or any directions on this upgrade would be appreciated.
ray,sorry to inject seriousness into this thread;you shd check that your headers WILL bolt up,i think the ports are a slightly different height,you will also need new valve covers,different bolt pattern in head,make sure your plugs also still clear the headers...john;32
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Originally posted by 77CVT
To actually answer the original question...... an L48 with mild cam, auto, 3.08 diff, re jetted Quadrajet, Edelbrock intake, stock heads, port matched intake with 2.02/1.6 valves, dual exhaust (no cats), recurved dizzy will take you in the vicinity of 220 RWHP.
A 750 is too big! You need to work out your airflow when choosing a carby. You'll find all you're drawing is 450-500cfm @ 5500rpm anyway.
Cheers
Spot on nuke ;27
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WR, I think you might need a different bellhouse to go from auto to man.? But it should mate up. I think you shoud get the 4 speed as well...its still attached, just drop 'em both in! Going Cheap!;29
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You know what would be the ULTIMATE big block-
the 632!
http://vetteweb.com/tech/0411vet_wp632/ (http://vetteweb.com/tech/0411vet_wp632/)
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I'm not so sure it would fit into a vette,the biggest bore/stroke on a standard deck is 540ci, But what they use looks the same but is a raised deck = so it sits taller (?) and then probably wouldnt fit?
http://www.sonnysracingengines.com/products/engines/7621570hp.html
Just to up the anti why dont you put this montser in.....762ci BB = same block as the 632! And the price is a very cheap US$66495!!!!!!!!
Add a bit of laughing gas and voila 1920HP .... then put a huge blower......;41
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rick moroso is putting a 572 in his 68 coupe now thats taste
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Just a qik addition to the hijacked half of this thread... VO mentioned to white rider the 400ci. From what i've heard i wouldn't go near one. they have a siamese bore, meaning water jackets don't go around all bores, but PAIRS of bores. in big hp engines this uneven cooling leads to bores going oval when hot... and for very little advantage.
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Thats a valid point but the old "cooling issues" opinions on the old 400 castings varies depends on who you ask.
From what I understand if setup properly for your application you shouldn't have any issues.
If I were going for big hp from a 400 block I would personally go for an aftermarket casting - better blocks suited to bigger hp and bigger capacities.
Just my two cents. :22
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Meanwhile back at the farm.
Vortec heads.
Best flowing stock cast iron GM heads made , outflow Bowtie heads.Based on LT1 Vette heads.
Can upgrade to 2.02 / 1.6 valves but that is all that is recommended as ports are so good stock.
Flow 190@.300
227@ .400
239@.500
Stock springs will only go .450 , need to cut valve guide boss down if wanting more lift and change springs.
Vortec cam won't fit L48 as a bolt in.It is a roller cam and needs mods to fit. Also needs roller lifters (expensive) and new pushrods..
Better to get a flat tappet cam to suit the flow of new heads and retain all your existing valve gear.
Exhaust ports are the same as stock , changes are on the intake side.
Need to check CR with new heads.
Vortecs are 64 cc , from memory smoggy L48 heads are 72cc so compression may become a problem.More than low compression L48 is better up to a point.
Cheap take off centerbolt valve covers can be had on US eBay for $20+.
If you want some expensive polished alloy ones see me.My new TFS heads take old style covers so my shiny new centerbolt covers won't fit
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Originally posted by Cameron 77C3
Originally posted by Brutus
What are the flow figures for the Vortec heads and also the camshaft specs?
You may also find that the 750cfm Holley is a little more than you need for that engine as is.
Agree with Brutus. Unless your beast is doing some serious RPM's a 650 should be fine.
My beast is reving to 6200 rpm, roller rockers, cam, etc with 355ci and the holly 650 double pumper, competition style, is fine. Bigger is not always better
I agree with the above (I know its a ford engine) but my engine makes power to 6k and I run a 650dp.
From memory you said you have a 330hp crate engine?
My engine makes 337rwhp and only needs a 650dp so would say you would only need a 650 vac sec.
I am not bragging, just trying to help make a point.