wondering about my mods

vetteKID · 03-15-04, 02:45 AM

i have a 74 vette and im looking to know what horsepower i have now and how to get a little more.

74 L-48 engine (195hp 275tq),60,000 miles (unrebuilt), super t-10. quadra-jet, stock bottom end, stock style clutch

mods-
performer intake manifold
accel wires and and dist.
block hugger headers
dynomax bulllets which dump before the half shafts
Crane Chromemoly Pushrods
summit cam and lifters
cam Specifications:
* Advertised duration: 272 intake/282 exhaust
* Duration at .050 in. cam lift: 214 intake/224 exhaust
* Gross valve lift: .442 in. intake/.465 in. exhaust
* Lobe separation: 112 degrees
* RPM range: 2,000 to 4,500
* Good idle quality

it has nice qualities right now, but its just not filling my need for speed. i was thinking a 50 shot of n2o, but that seems alittle drastic. money is kinda a concern. however i would like to know what you guys think i have horsepower wise right now and what my next step should be.

AKRAY4PLAY · 03-16-04, 12:57 AM

heads are on the top of my list. the cam you have is very conservative, but works well with stock heads. better heads and a hotter cam will wake her up. Brian

oh ya, you are probably around 230-240 hp depending on condition of cylinders/rings.

vetteKID · 03-16-04, 01:41 AM

what about roller tip rockers?

Glensgages · 03-16-04, 08:53 AM

Quote:

Originally Posted by vetteKID

what about roller tip rockers?

On a relatively mild motor like you described, not needed, but can't hurt, especially if you plan more drastic mods in the future.

AKRAY4PLAY · 03-16-04, 11:57 AM

Quote:

Originally Posted by vetteKID

what about roller tip rockers?

roller tip rockers don't make a drastic reduction in friction. they mainly keep from side loading the valve stems and wearing out your valve guides. if you want the rewards of rollers, you need roller lifters and full roller rockers. Brian

TexasShark · 03-22-04, 05:52 PM

You didn't mention it, but if you haven't yet addressed it, I'd look to upgrade the exhaust. All the mods in the world won't reach their full potential unless she can exhale! FYI -all engines are the same (including people), the harder they work, the faster they have to get rid of waste.

Good heads, a fat stick, hot spark and lots of cold air

.

bossvette · 03-22-04, 05:58 PM

bring it to cruise fest and take it to the dyno-run

vetteKID · 03-23-04, 12:24 AM

Texasshark- I already have exhuast. its 2.5" pipes with flow through mufflers(dynomax bullets) which dump under the passenger compartment. should i upgrage to 3" exhuast?

whats cruise fest?

vetteKID · 03-23-04, 12:26 AM

could my car handle a cam upgrade with out new rockers?

cam upgrade Specs:
* Advertised duration: 282 intake/282 exhaust
* Duration at .050 in. cam lift: 224 intake/224 exhaust
* Gross valve lift: .465 in. intake/.465 in. exhaust
* Lobe separation: 114 degrees
* RPM range: 2,200 to 5,200

Jack · 03-23-04, 02:41 AM

Yes your OE rockers can handle .465" ... but I'd offer that such a cam is a very tiny upgrade over the one you have ... not worth the time or expense to change IMHO.

A simpler way (but just as expensive) to get more valve lift is to swap out your old OE 1.5:1 ratio rocker arms with a set of 1.6:1 ... effectively lifts valves .471"/.496" respectively ... emulates a bigger cam ... but your OE valve springs cannot support that.

Keep in mind ... you're working with a relatively low compression motor (L48) ... you cannot successfully use a lot of cam with little CR. You are limited by low CR. The bigger the cam gets ... cam's size effectively bleeds-off the motor's CR ... which is why the bigger cams need a motor with more CR.

Chances are your heads have about 76cc chambers, likely pistons are dished w/ 4 valve reliefs yielding about 10cc of negative dome volume and the pistons are probably anywhere from 0.025" to 0.045" down in the hole (below deck).

I'm not a big fan of nitrous ... but your cam choices are constrained primarily by low CR ... so a small shot of gas on those relatively weak cast pistons might be the ticket ... or a rear gear swap.

You're stuck with low CR unless you change to small chamber heads/flat top pistons/deck the block/surface the heads. More cam will only serve to lower CR even further.
JACK

bossvette · 03-23-04, 04:04 PM

CLICK for complete info on the 1st CruiseFest in Auburn.

Quote:

Originally Posted by vetteKID

whats cruise fest?

My sig has a link to it, but if you click on the forums link at the top left of the page it is on top of the list. Cruise fest is the first national CAC get-together being held in Auburn Indiana this May it is a CAC only event so it will not get swollowed up like at Carlisle. Some of the events require pre registration and if you want a t-shirt or dash plaque you better get moving on it. Call the Hotel direct and tell them you are with CAC to get the discount. We are planning a banquet at the ACD museam which includes all day museam admission which requires pre registration (Cooks need to know how much to cook

)
There are many other hotels/motels in the area and there is a link to Auburns web page for attractions
It will be a fun time for all and a chance to put faces to the screen names, I just hope I don't scare too many away when its my turn at the registration table

there are caravans forming from the East(NJ), North (Mich) and West (Ca.) check the threads about them.

Evolution1980 · 03-23-04, 05:26 PM

Quote:

Originally Posted by AKRAY4PLAY

heads are on the top of my list. the cam you have is very conservative, but works well with stock heads. better heads and a hotter cam will wake her up. Brian

oh ya, you are probably around 230-240 hp depending on condition of cylinders/rings.

I'm with AKRAY4PLAY on this one. It seems that heads is pretty much the last easily accessible top end component you haven't replaced. Since you are running a Performer Intake, and non-oem cam, check with Edlebrock on a good matching set of heads for your engine. They should be able to find something that'll give you some noticeable results on the buttdyno.

Heads will probably set you back between $500 and $1000.

Keep this in mind for future reference. I was faced with these same types of questions a few years ago. After all is said and done, you are going to have many new parts in an older engine. Granted, you can do this over time and it's a bit easier on the wallet. However, you may want to consider just getting a new race-prepped engine if you really want some bang for your buck.

Advantages to a new engine?
1) Brand new engine with matching parts and known power ratings
2) Warranty!
3) You now have a working spare if you manage to blow up the new engine
4) Pawn the old engine off on ebay or private sale apply it to the cost of the new engine
5) By a ratty GM car and drop your 350 in it for fun. (a Fiero comes to mind...hahahh)

I had about 68K on my L48 when I started kicking these things around. After doing the whole top end of the engine (for around $1500 or so), that still left me to make sure the bottom end was rebuilt...Another $1000 or so. And it's still all housed in an old block with wear. So we're at $2500 +/-. Or..I could just go buy a new engine and be done with it all. Yeah, I had to save my pennies a little longer and little more aggressively. But the smile on my face when I fire up the car is worth every penny!

69autoXr · 03-24-04, 12:32 PM

What is your rear gear ratio?

vetteKID · 03-24-04, 12:35 PM

3.55