thomas1976

I need some help here. After doing all the first time mods tgo members suggest to my lo3, what is next?
I have full exhaust, cold air intake, performer tbi manifold with 46mm bores, lt1 cam and chip.
I read close to 280hp should be possible with stock heads, but how do I get there?

kdrolt

IIRC Dewey316 got 208 rwhp with a similar cam, stock 187 LO3 heads, exhaust, CAI and probably some good tuning. That's approx 240+ fwhp. He jumped 16 rwhp when he swapped in some ported 416 heads. IMO you would experience similar gains if you ported your stock heads the way HRM and Fast355 have done on equivalent swirl port heads. But you'll still be short of your goal: like Dewey316, you'll be around 260 fwhp.... well short of the 280 you want.

To get to 280, you will need ported heads AND a larger cam than the LT1. You'll also need to look closely at the fuel system (are the injectors large enough? Do you need larger injectors, and/or higher fuel pressure) as well as retuning the combination. HTH.

TonyC

iTrader: (1)

I hit 216 rwhp, 266 rwtq with the following combo:

Edelbrock Performer EGR intake
LT1 cam with Z28 springs
SLP 1 3/4" Headers
Electric cutout after the y-pipe (before cat)
14x3 K&N open element
Ultimate TBI
LT1 Rear with 3.42 gears
Aluminum D/S
MSD ignition
Custom PROM (Prominator)
Through a T-5

I think you'd have to port the stock heads to get 280 crank hp

Fast355

iTrader: (2)

You don't have to port the stock heads to get 280 crank hp. You don't have to port them to make 300 crank HP. You just need to run a bigger cam than the junk LT1 cam. That cam only made 275 HP on a 350 with great flowing intake and heads. I made over 245 RWHP with a stock pair of unported 187s, through a 700r4 and 9.5" corporate 14 bolt rear-end.

thomas1976

Thanks for the replys. So there is no power left in my stock heads combo without putting a better cam in or a cut out and a t5.

Basicly I will have to do some research on changing the shift points at higher rpms with my 700r4 to have to full benefit of the cam.

Fast355, what big cam do you suggest fits this engine? I put compcams 981-16 valve springs, would I need to change them to? And how will it be out of the hole? I suppose you got tose numbers way above 5000 rpms.

TonyC

iTrader: (1)

I'm sure you know more than anyone that the LT1 cam has been a great, inexpensive upgrade for a lot of people on this site. $40 for a cam isn't a bad deal in my book. Was the 245 on a 350? Cam?

Dewey316

I agree, More cam and you can probably get there, but not all the effeciantly. If the bottom end is in good shape. I would be scared to spin my motor any furhter than I am now. BUT, a bigger cam and more revs, I could have probably gotten 230-240 out of those heads. BUT I did get those numbers with junkyard 416's with the 1.84 valves in them still, so take it for what its worth.

funina91ss

I just got back from the dyno today and I made 208rwhp stared out at 178rwhp I think the tq went to 268 or so. I picked up over 75ftlbs in some spots where I was going way rich. I will post up the graph and actual #'s when I get the file.

But on a side not I made 320rwhp and 442 rwtq on a 150 shot I am hopping to see very low 12's or if it works out really well might get a 11 sec pass out of it.

Regal105

i'm wondering, everyone knows how the lo3 head sucks as far as flow in concerned, with the ramp in the bowl, i have a couzin with a bridgeport mille
would i be able to shave off this ramp and bump up my cfm? i know ill have to polish the port once it's done.

Dewey316

You don't want to polish the intake side, you want some roughness, it will help keep the fuel in suspension, and not condisate on the walls.

If my 305 was younger, and not as sloppy, I would probably have worked on using SP's with some porting, just to see what they do. They have good exaust side flow. But, honestly, with 230k miles on this motor, I'm not going to try anymore, lol. I'm going to beat on it until it lets go. I already have plans for the next motor, and plans to go a whole new exciting route with TBI.

I would be interested to see numbers side by side with ported 416's, or other standard heads, compared to the ported swirl-ports. It would be an interesting test that no one has really done. Use same cam/motor, just diffrent heads and run it on the same dyno and see what happens.

--John

--Funina91ss -- Did you ever get track times, I have never gotten a really good track run, or dyno run with the nitrous and motor really working right on my car, I always seem to have problems (last dyno, it was 26* out, and I have not bottle heaters...). So I have never run at the track with the 150 shot to see what I can do. With the 100 shot, I went 13.3 @ 107 but I am making about 30rwhp more than you on my motor. I'm hoping with the 150, I will finaly pedal my car into the 12's one of these days. lol, I know it has it in it.

funina91ss

Yes I did Here is the video of my best pass so far. I ran out of gear in the 1/4. My NA passes were 103 mph on the spray it was 101 lol.. Should of went around a 12.2X if it had the gear for it.

http://s154.photobucket.com/albums/s...nt=clay026.flv

TonyC

iTrader: (1)

Do you mean 93 mph? 103 mph is good enough for a mid 13 second pass easily, no way a 208 rwhp car is trapping 103 mph unless it weighs like 2000 lb lol

edit: Sidenote man I need to get my *** in gear and get going to the track!

funina91ss

I went back and looked at the time slips and I posted the wrong mph.


NA

1.96
9.15
74mph
14.31
97mph

N20

1.76
7.88
88.76
12.49
101.60 mph only 3mph faster than the NA 8th mile run.

If I didn't have to let off I would say it would have went 12.20-.30

Dewey316

Urgh... I hate guys like you.

I have trapped as high as 106, but can't pedal into anything better than a low 13's run. and that was on a 100 shot, with the 150 shot now, I should be trapping in the 108-109 range. I just have to figure out how to get the stupid thing into the 12's.

Are you on street tires, or running DR's ??? I haven't managed better than a 2.1 60' time, if I could get a 1.7 sixty, I should be pretty well into the 12's.

campin1983

iTrader: (4)

Care to share? I'm working on idea to replace my L03 and I still haven't decided on intake options yet. I'd be interested to know what your working on

funina91ss

I am running MT ET Streets. Mine would hook better if it wouldn't bog off the line if I heat the tires up to much.

Dewey316

Umm, it will include more cubes, a redline of around 8500rpm, and some boost...

USchevyMC

Fast355, or anyone, whats the biggest cam would fit with the stock heads?

-Mark

Dewey316

Generaly the limit on the stockers is around .470 - .480 or somewhere in there. If you start getting close to that, you are going to want to really check the clearances when you install it.

My old stock heads are sitting on a 355 in my freinds car right now, with a cam that is .474 lift, and it doesn't have any clearance issues.

USchevyMC

Alright, so would one of these work well:

http://store.summitracing.com/partde...2&autoview=sku


http://store.summitracing.com/partde...4&autoview=sku


Mark

Dewey316

Those are both flat tappets, what motor is this going in, and what mods have you done, etc, along with your ability to tune. There is a lot more to picking a cam than jsut the lift number.

USchevyMC

Well i got hooker shorties, and a hooker y-pipe with no cat, and a cat-back system, and an open element, i also plan on getting a new manifold and i am also getting an EBL flash. I have no clue how to tune and was just planning on taking to a shop to tune it unless i can figure it out soon haha. Its going in my 92 305 TBI, and its got only 43k original on it.

vjo90RS8

iTrader: (1)

if you want a faster car I don't think you need to look at the engine anymore, especially if you want to keep the stock heads. Some 3.73 gears and a 2400 stall TQ should be great upgrades for your car. I was running mid 14s with stock cam, intake, heads, and tbi.

Dewey316

Niether of those cams are what you need. You have a rolller-camed motor. If you want cheap and proven to make OK power, the LT1 cam's are pretty common. If you want more than that, you will need to look for a cam grind for a roller motor.

USchevyMC

Sounds good, and I know that this has been asked and i have looked at other stickies, but will any LT1 work right?

DM91RS

All roller cams from GM after they started installing them will work until the LS engine family.........IIRC