Trx450rida

looking for some advice im wanting to get a little more power out of my motor. the car is a 92 camaro 3.73 gears eaton posi unit 3500 ptc torque converter built 700r4 trans.

the motor was said to be pushing around 450hp/450tq not sure about the numbers this motor was a gift

355 sbc
edelbrock performer rpm aluminum heads
edelbrock performer rpm air gap intake
comp extreme energy 284h @ .050 240/246
650 speed demon carb

some guys have told me that i could upgrade my cam and get some head work done and it would get me well over 500. the car runs pretty good for what it has but i want more would like to get mid to low 12 second car this will be a weekend car only and taken to the track few times a year. best time so far is 13.6 street tires flashing off the line no stock v6 shocks all way around will upgrade eventually wanted to get motor lined out 1st

the question is with the parts listed does the power ratings sound right and if so if not what would you recommend as far as cams and other upgrades i heard a bunch of good stuff about ultradyne which they guy said they dont make any more but im open for suggestions thanks in advanced

dmccain

iTrader: (2)

Get a Holley 750 Double Pumper and some Slicks and you may get in the 12s with just what you already have.

Trx450rida

what about if i add a 1in spacer would that justify for more air flow that the 750 would give me i bougt the carb a few months ago and i doubt they will let me trade out being used and really dont want to spend another 5-600 bucks on carb

Night rider327

iTrader: (13)

What was your trap speed? What was your 60' times? Trap speed shows your power, 60' times shows your traction.

13.6 is very SLOW for that combo.

What is your exhaust system?

What you have there should be well into the 12's with no prob... I was running in the mid 11's with much less engine than you have but with a well working suspension/chassis

The 650 speed demon is not really that big of limiting factor for you right now. IMHO at this point not worth even looking at changing that out yet. You have some other things that is limiting you with what is already there.

Lets try to work through those 1st.

What is your tune? Timing? Jetting? Spark plugs? Ignition system?

Like I said. based just on the gear, stall, heads, cam, intake, engine size you listed it should be a 12.40 to 12.80 second car with traction easy.

Trx450rida

hedman long tube headers dual exhaust 2.5 in pipe dyno max bullet mufflers

hei distributer timing set at 35 total

8.8 mm accel wires

champion spark plugs from orielly cant remember the number im out of town right now

stock carb no change with the jets

fastest trap 101 13.6 1/4 mile

60' i believe 1.8 is my fastest i believe.... my slips are at home

i know this motor was in my dads 72 c10 3.73 no changes and his fastest time was a 13.2/13.1 at 98 if im not mistaken he had turbo 350 with 3500 stall and he could stall up off the line. i figured even with street tires id be closer to 12's just going off being over 1000 #'s lighter if im not mistaken... i can only get to about 2200 before tires start turning so i just flash it off the line i was thinking not being able to stall up is hurting me also but not sure about that

Trx450rida

Time slip

Night rider327

iTrader: (13)

I don't think its your stall/launch rpm. Most foot bake racers leaves the line at 1200 to 3000 rpm. In your case higher launch pm would just cause more tire spin.

Power is WAY down on this engine across the whole board. Nothing really looks out of place or jumps out at me, just lacking power from start to finish of run.

Those times are inline with a 290-300 HP engine, but with your specs you should be above that.

I would look at your carb jetting 1st. I think you may be lean from off idle and up.

What compression does the engine have? Dish or flat top pistons? That would be my other thought... It's a low compression engine with too much head, cam, intake for the compression.

cuisinartvette

overcammed/undergeared
Id put less cam to it you may be pleasantly surprised. The 650 is plenty

Trx450rida

The motor is supposed to have flat top pistons and he said compression around 10.1-10.5.... I actually took to dyno and was highly upset with numbers I only put out 267 torque and 250 hp to rear wheels but he said I was around 390 or so cause the 3500 stall would take away between 45-50% from dyno number due to slippage..does that sound right???? He said air fuel reading was good according to dyno.... If cam is to big what would you recommend I've heard good things about the lunati and ultradyne.... I know I don't have a tire on there yet but like I said my dad had a 72 c10 and he went 13.2 with same combo with tire. I know a tire will help me out but i figured I'd have better times than what I'm putting out just by going off weight.... Next time I go I will be putting a tire on

Trx450rida

Any ideas????

Night rider327

iTrader: (13)

NOOO that does not sound right at all. Aint no way in hell that engine will make 390 HP to the wheels... The converter is not going to show up as a 40-50% loss due to slipping.

If you are making 250 HP at the wheels...You will loose 18-25% through the drivetrain.
You have about 290-310 HP at crank..

Which back up in post #7 I est. your engine to be 290-300 hp based off your time slip before I ever knew of your dyno numbers.

The parts list sounds more impressive than 300 HP but something just is not there for the power and my guess is that it's a low compression engine with too big of cam, heads, and intake.

Trx450rida

Starting to make a little more sense now I was told motor should have over 400 horses but I knew I wasn't getting that performance I think is why I'm so upset with the way it's running.... Anyway what compression should I be running I thought 10.1 was good but who's really knows what's in the motor like I'm supposed to have 400+ horses.... Or what do I need to do to get into the 450 power range all motor

redneckjoe

nitrous and better tires should make a big difference.

Trx450rida

Yes I know I can add nitrous but don't want to go that route with the combo that I listed don't you all think I should be making more than 300 horses at the crank.... What do I need to do to get in the 400+ range

midias

With that cam your idle should be fairly rough and 400+hp is not that hard. Something is very wrong with your combo to make that little. Maybe a wiped lifter or something.

Personally the XE274 cam is about the biggest flat tappet cam I like on street 350s but I am starting to feel like nothing beats A GOOD ROLLER cam

Night rider327

iTrader: (13)

Alot of your probs sounds like simply tuning trouble and maybe something little hindering your power.

You CAN NOT look to add parts to make more power until you really know what you have now and why power is so low.

That is NOT a 450 HP build list but it damn sure looks like 400 HP parts list to me. You are down a good 75+ HP... Need to find out why 1st.

To do that, you need to find out what you really have, and what is going on.

Rather than spending a dime on parts at this time you would be far better off to spend $200 on a good advance digital timing light and a vac gauge if you do not own them yet.

Check your timing at idle and every 500 rpm up to 4500 rpm and write that down. This will tell you your timing curve and if mech. advance is working right.

Check your throttle cable and make 1000% sure the pedal is pulling the carb to true WOT. See this one many times where a combo of cable, bracket, stud, etc does not allow for true full throttle pull on carb when you floor the pedal.

Check your vac at idle and cruise rpm.

Adjust idle mixture screws to get highest idle vac levels,

What part # is on the heads, need to know if they are 64cc or 74cc or what ever.

Do you or anyone you know have a bore scope so you can look in the spark plug holes and see what pistons?

For that matter what plug # are you running.

Trx450rida

i will check this when i get home tonight i do have a digital timing and vacuum gauge i will let u know these numbers later tonight and make sure im getting full throttle

Trx450rida

I have completed some of these test
Part number on the heads are 6089
Plugs are ac delco 41-629 i noticed on the plugs I pulled there was oil all around the threads none on the tip but threads was covered
Vacuume at idle 17 degrees @ 800rpm was at 6hg I didn't get to drive and check at cruising due to weather
Initial timing 17 degrees
1500....30
2000....32
2500-4000....35

Was only able to check 4 plugs 1 was at 160 the other 3 were at 155

I am getting full throttle out of pedal
As far as pistons I didn't have a bore scope but they are supposed to be hyperutectic dish

Night rider327

iTrader: (13)

"hyperutectic dish"

You said dome pistons in one thread, flat top pistons with 10 to 10.5:1 compression in another. Now dish... Which is it?

If it's dish pistons, we can end the witch hunt now... You do not have enough compression to run that cam, cam is too big and compression is too low...

The 160 and 155, is that your cranking compression? If so that sounds about right for lower compression, big cam engine... Your wanting 180 to 200 psi cylinder pressure for performance engines

D_Smith87

I think you are in the realm of a mismatched motor, the cam to intake to heads sound good but if i had to guess either that cam got wiped out, its flat tappet right? Or you have some 7.8-1 pistons on a cam that needs a 9.5/10-1 set of pistons or possibly a valvetrain issue, people often cut corners on valvetrain which is terrible because its detrimental for a motors performance and efficiency, ive read plenty of articles where motors are down 50-75 horse from where they should be by a low compression issue alone. Another thing timing, if i were you id degree that cam to make sure its where it should be.

Trx450rida

Yea see that's the thing idk what pistons are in it he said he thinks dish or dome and I don't have a scope available can you get those at a parts store autozone or something.... Now that we have come to conclusion of a low compression engine what Pistons would you recommend or could I just get cam replaced to match the low compression of the engine would that make it run better than what it is now.... Either way I plan on jerking it out this winter or sooner and doing it right

midias

You can get a cheap scope at harborfrieght. Or you can just pull the heads this winter. If you pull the lifters make sure to put them back in the same place.

D_Smith87

As far as pistons get some 9.8ish to one flats or some small domed, maybe 10.5-1, reason be with 10.5-1 theres even more room for future cam
Upgrades without needing to swap pistons, if you go dome check your clearances thoroughly, last thing you wanna do is smack a piston with a valve

Trx450rida

If I go with 10.1-5 you recommend flat is that correct???? And what's a good brand???? And would that work with the cam I'm supposed to have???? Like the scenario I'm in now is there a thing where I can have too much compression and not enough cam???? Also what other cams out there would you all recommend for this set up one I get everything lined out.... I've heard ultra dyne is about the best you could get but also heard they don't make them anymore

Night rider327

iTrader: (13)

Yes you can get too much compression and not enough cam... In that case you would be worse off than you are now. Now your just lacking power.. The other way with too much compression and not enough cam will cause detonation probs unless you run race fuel and detonation will destroy the engine..

Just hold your horses man, you are alittle to eager to start swapping out parts. You need to know what all you have and then build a game plan.

You have a few options but need to know more about what you are starting with.

You can change the cam to something smaller, it will pick up torque, feel better, more response, be overall better but HP will still be low. In the 300-325 at crank range.

You can keep your cam, and change out pistons, get compression up and pick up gobs of power. Takes a lot more effort and money to swap out pistons though. Then of course you need to know if the cam is really what it was said to be.

You can keep what you have piston and cam wise and have the heads milled down to a smaller CC chamber

An engine needs to have all of the parts matched to each other... Cam and compression has to match up to get you the correct DCR/cylinder pressure. Then the heads have to match the engine size, rpm range, and cam..

If your cam really is what you was told, then you need 9.8 to 10.4 range compression.

When figuring compression it is a lot more than just the pistons.. It's the pistons CC volume, how far down in the bore the piston sits at TDC, the head gasket bore and thickness, and the head chamber volume.

Again depending on what you have, you MIGHT be able to swap head gaskets and get your compression up enough to run that cam and make better power.

The common rebuilder type head gasket is 4.166" bore and .041" thick. If you have head gaskets of that size going to a 4.100 x .015" gasket will pick up 0.67:1 compression...

Pistons... I like JE, Wisco, SRP, Howards, Speed pro, sealed power and KB in that order.

Cams. Yes ultra dyne is good, so is Howards, Luntia, Crane,

Trx450rida

Yea I know I'm pretty anchious about getting this running better. Lol... I think my next thing I'm going to do is remove the head and see what Pistons i have then go from there.... But until I actually dig into motor I won't know what I really have

D_Smith87

Thats probably a good start, who knows you could have some 7.8- pistons

67Blast

I agree with most other replies. However, a simple cranking compression test could reveal alot. My 355 in my Chevelle has 186 lbs, on average across all cylinders. But be aware that cam overlap affects cranking compression. Ive been 7.80's on motor, in the 1/8th. and drive it everywhere. I know thats not fast, but for a 3400 lb. small ci. street car, with no power adder, its decent.
The 650 carb is fine on a 355, too. As throttle bore increases, throttle responce decreases. Air speed decreases across the plentum and torque suffers.It works in every part of the engine .Not just the intake.
Cylinder head flow, namely low and mid lift, are very important. Max lift flow doesnt mean squat unless you are lifting the valve to max flow.
Torque production or lack of, for that matter, is very important for a street and race car. Torque moves the car.
I have a friend who has been 5.0's with a NA 540ci. in a '91 I Rock. It traps at 140mph in the 1/8th. You can look up Kruck Racing on FB. Best I can remember, he uses a 4.10 gear.
(Right now, is when most people will freak, and say it cant be done) But, I assure you, it can.
Last weekend I whitnessed a small block car go 4.86, 4.87, and 4.82 at 153, three times in a row in Cheep Street trim.

A properly tuned exhaust is also part of an engines power. Shoot for 2 lbs. or less backpressure before the muffler. Hardly anyone checks for this. Hardly anyone who doesn't know better, that is. But it makes a difference. I use Dynomax mufflers simply because they flow their mufflers. And they put it where you can see it. Im pretty sure their 2 1/2" in and out will flow 488cfm, each. So, one will support 244 hp.
In all honesty, I think your cam is too big, now. Unless, you have 11:1 compression, which will have over 200 lbs, cranking compression , gear the car for the powerband, use a larger carb to wing the 355 to 7400, use a 4000-4500 stall, etc.
Its JMO, but Susan Howes '90 I Rock runs 7.0's with a Natural Asperated , 355.
If I were you, before I spent a dime on my engine, Id buy a MSD7531 or a Grid, have it installed, learn how to use it, and plot runs. It is the "ONE" most useful tool, in racong today. The technology offered is second to none. You can adjust timing, traction, gear retard, time individual cylinders, launch retard, launch rpm, etc, etc, etc.
There is no way we could run these low numbers with such high trap speed, without them. And that is exactly why, they are becoming, normal on even 12 second street cars.
You can expect to spend $1200 for the controler and $400 to put it in. But, I swear it will have more features than you could ever learn, and it will help you be faster than anyone without it.

67Blast

Sorry, it posted twice..