raptere

Snowed here too, but it sunny and 43 here right now! Fingers crossed!

Everywhere I have read said you want a negative 1-2 deg difference from having your trans and rear end pinion parallel to account for winding of the rear end under load. Even the installation instructions from BMR the maker of my torque arm. (And UMI, who for similar products often has better installation instructions...)

BMR:
Set the pinion angle using the following method: Load the rear axle by either setting the car on the ground or letting the car rest on jack stands positioned under the rear axle. Place the angle finder on the driveshaft and record the angle. The driveshaft angle is negative if it slopes downward towards the rear of the car. The driveshaft angle is positive if it slopes upward towards the rear of the car. Now place the angle finder on the rear end torque arm mounting plate and record the angle. The rear end angle is negative if it slopes downward towards the front of the car. The rear end angle is positive if it slopes upward towards the front of the car. Add the two measurements. This is your pinion angle. (Example: -2 rear end angle plus -1 driveshaft angle = -3 degrees) Turn adjuster to achieve the desired angle. As a starting point, most F-Bodies seem to like the following initial settings: Automatics: 1-2 degrees negative Manuals: 2- 3 degrees negative

UMI:
How to Check the Current Pinion Angle- To check the current pinion angle the vehicle must be level with the suspension loaded. Place the angle finder on the drive shaft and record the angle. Now place the angle finder on the bottom plate of the torque arm where it attaches to the rear end, record this angle as well. To achieve true pinion angle you must add the two measurements. For example if the drive shaft measures 0 degrees and the torque arm mount measures -1 degrees you have -1 degrees of pinion angle. We have found the best settings for a street driven car are: Automatics 1-2 degrees downward, manual 2-3 degrees downward.



Were also talking about 1.3 deg, the video shows more like a 30 deg misalignment... So hopefully it doesn't cause anywhere near as much oscillation

QwkTrip

iTrader: (22)

GM service manual lists specs that result in 0.4° angle and that's with squishy stock springs and stock torque arm that allows some axle wind up. Given your firm setup you can set your u-joints to near 0° and you'll be golden. Ideally you want to end up with 0° during the majority of your drive cycle which is low throttle driving. Your torque arm and coil spring setup is a lot more resistant to axle wind up than the old leaf spring cars.

QwkTrip

iTrader: (22)

I think I know where is the confusion. Stock specs are the working angle of the u-joints is between 1.0° to 1.5° in our cars. And the two u-joints should be parallel within 0.4°. Your non-stock suspension can be closer to parallel than that, approaching close to 0°.

The longer you're in this hobby the more you'll learn to not trust places like BMR and UMI to get the details right.

raptere

First two day autocross event is now under my belt. It was really so much fun! The first day it rained most of the day, but the second day was dry. I was able to get in 20 runs across the two days. Started getting a scent feel for the car, but after all these recent mods, it was like a new car! I'll have to continue to learn it's limits. I really think, with all your help I nailed the mods necessary without going crazy, to have an effective and capable car. Definitely more capable than I am at this point!

Only two issues came up. First my ac compressor which I knew was locked up, so I previously disconnected electrically, now decided the clutch was going to start dragging. Made a terrible racket and smoked at times, but I know I needed to replace it alredy so whatever.

The second concern I have are my brakes. Currently factory 4 wheel disk brakes with hawk pads and power slot front rotors with braided stainless lines and flushed with dot 4 fluid. Well... they just kind of suck... the pedal is pretty soft with the engine running, when I get on it the bedal goes nearly to the floor. With the car off the pedal pumps up nice and hard. The rest of the parts are factory, so I'm wondering if it's time for a new mastercylinder or something. I understand the seals wear out over time and can cause sponge brakes. Is this most likely the culprit? I'd like to put in the c6 vet brakes at some point, but if my MC is bad, I definitly need to deal with that first. They would fill the 17" wheels much better though. Factory front brakes look comically small right now...

thedevilinside

Good vacuum? Air in lines? Master sizing and condition would also be things to check like you said.

QwkTrip

iTrader: (22)

A pedal that over travels is either air in the system or brakes lines that flex (expand volume) under pressure. Or it could be dimensional slop in the mechanical parts like worn pin on brake pedal, push pin too short, or rear brakes are not adjusted properly with a rest position too far from rotor. Your master cylinder probably has nothing to do with it other than maybe still holding some air.

Stock brakes do suck though, it heats up quickly and you will experience a lot of brake fade.

raptere

So, regarding pinion angle... I'm getting more confused... I've just been reading for another hour. There are so many different procedures, from manufacturers, and people online, and many appear to directly contradict themselves.... do ypu want the trans tail shaft to be exactly parallel with the rear end pinion, or do you need to add some sort of downward angle from parallel to allow them to become parallel under load? And is the amount suggested, 0.5, 1.0, 1.5 degrees below parallel, compensating for cruising load, moderate load, or full pedal to the floor load?

QwkTrip

iTrader: (22)

I think you're an engineer if I remember right. Go to the safe-source of information. Spicer media library, https://media.spicerparts.com/media
Search for the words Universal Joint and have fun with your research this weekend.

Now you got me kind of interested too. One document that catches my eye is the Driveshaft Installation Guidelines, https://media.spicerparts.com/cfs/fi...store=original

Just a few observations after a quick browse:

Looks like they recommend the U-joint operating angles to be small as possible between 1- 3 degrees, and not less than 1 degree. These are the U-joints themselves, not the parallel between U-joints. I can't quite wrap my head around why the 1° minimum but that's what it says and there's got to be a reason. GM specs for our cars are between about 1.0 - 1.5 degree so that's consistent with Spicer guidelines.

To cancel vibrations they want the U-joint operating angles at each end of driveshaft to be equal within 1 degree. This is the parallel between U-joints and obviously the closer to 0 degrees (perfectly parallel) the better.

The operating speed chart doesn't show specs higher than 5000 rpm but the trend is the higher the speed the smaller the U-joint operating angle has to be. This chart gives insight to where the 3 degree max comes from, looks to be an assumption specific to ~5200 rpm max speed. Well, I don't know about you but I can turn 7000 rpm in 4th gear and that's maybe around 1 degree extrapolating the data?

I also found this document for Driveshaft Application Guidelines and it's a lot more technical, https://media.spicerparts.com/cfs/fi...store=original

Anyway, after you explore that media library you'll probably be the smartest person on this forum about U-joints!

QwkTrip

iTrader: (22)

At the end of the day you're going to have to decide how much you think the axle wraps during the majority of your drive cycles. Setup specs in the GM service manual seem to imply that GM thinks the stock setup wraps only about 0.4 degrees (that's the way I'm interpreting it). Cars with stiff springs and strong torque arms wrap less, especially torque arms mounted to frame.

A lot of the conversation on the web is muddled up by carrying over specs from leaf spring cars that have more axle wrap. And some people are misguided by practices of drag racers that set pinion angle with preference for increased downforce on tires.

Beater79TA

For your brakes, open the hood so you can see the booster and master from inside the car. Sit in the driver's seat and press the brake pedal hard while watching to see how far the booster and master move. You may need to build a brace to stabilize those parts. At one point we had a soft pedal issue and it was because the booster and master were moving almost an inch in a vertical arc when the pedal was pressed.

If that isn't the issue, check for air in the lines and bad hoses. Stock brakes aren't great but are adequate for a lot of autocross with the right pads and fluid. I suggest you get a high temperature fluid not just a DOT4. This type of driving generates a lot of heat with limited time to cool between hard braking moments. A high temp fluid will go a long way to helping your brakes be effective on track.

raptere

Few things to update. I did go back and set the pinion angle to between 0 and 0.3 deg down. Before driving on the highway, i would hear a faint "wah wah" sound which I suspect was harmonics of the drive shaft. Since reducing the angle between the trans and the rear end, that noise has completely gone away! So I'm considering that one fixed.

Regarding the brakes. When I first did change out my fluid and flush the lines, the fluid was very dark. I have read that to mean it may have debris from failing master cylinder seals in it. I found a reman master cylinder for cheep that comes with a bench bleeding kit, and plan to install that when I UPGRADE MY FRONT BRAKES. I admit, I did too much reading on here and got all exited about upgrading my from brakes. From what I read, the rears brakes are acceptable, so I'm leaving those for now. I was able to find a good deal on the Cadillac ATS Brembro fixed 4 piston Calipers (same as on the C7 Stingray) , which run with 12.6" Calipers from the Vette, which should fit nicely inside my 17" ZR1 wheels. I'll be able to remove the .25 spacers when adding the new discs, and the remaining 2" spacer should be perfect! Resulting in the same track width I currently have.

I posted elsewhere as well, but is a reman of the original master cylinder for a non 1LE four wheel disc car adequate for these larger calipers? Is there something logical to upgrade to? Some standard part from a later model Camaro or Corvette? Maybe our generation 1LE master cylinder if it is any better, and if it is available?

Beater79TA

Dark fluid is also a sign it simply needs to be changed. Heat cycles and water contamination will also cause it to look "burned" or dark. You MC is probably fine if there was no debris in the fluid. Racing will cook the fluid and cause at least annual fluid flushes.

The factory brakes system (booster, master, prop valve) are capable of operating much larger than stock brakes. We run the stock booster and master with a Wilwood adjustable prop valve with 14 inch 6 piston front brakes and 13 inch 4 piston rears with no issues.

raptere

Interesting. I thought I had read dark fluid is often a result of deteriorating seals and fine little particles of the seals them selves suspended in the fluid. I was honestly hoping there would be improvement to be had by replacing the master cylinder, its just so spongey now... I guess I install my new brakes first and see how they feel. Then, decide if it is worth trying to replace the master cylinder...

I did also want to ask... Long ago, I installed an SLP line lock for the front brakes, back when I thought I was going to become a frequent drag racer, of course that never happened... So is there a chance there is air trapped somewhere in that assembly or the additional adapter lines that run between the master cylinder and the proportioning valve? Would it be a good idea to just remove it while making my other brake changes, or is it very unlikely that it is having any negative effect on my brakes? Is there any use for a line lock (front brakes) for autox or road racing?

91banditt2

iTrader: (1)

Sorry I'm a little late to the thread, other than TGO, FRRAX is also a good source for asking for advise from people experienced in setting up car for Autox and road racing, in the past two years of working on my 91 Firebird I've learned alot from the fellows there
F-body Suspension & Chassis Intro - F-Body Road Racing and Autocross Forums (frrax.com)

Suspension Advice - F-Body Road Racing and Autocross Forums (frrax.com)

raptere

Just to connect it all, I am making good progress on my ATS (C7 Base) brake upgrade you can read more about it here!
ATS (C7 Base) brakes on a 91 Z28 - My Experience - Third Generation F-Body Message Boards

Regarding the brake fluid. I just sucked all the brake fluid out of my master cylinder, wiped it clean, and put in fresh, as well as flushing all four lines about 2 months ago. While installing my new front brakes, I went to open the master cylinder reservoir and found this. Both sections looked like the front section, but I topped the back one off so it stirred up whatever that is. Could that be the remnants of disintegrating seals? I have competed in two autox events since then, and road driven the car a few hundred miles...

91banditt2

iTrader: (1)

What brake fluid are you using, for my project car which I’ll be using for auto cross and some road racing events I’ll be using the Motul RBF 600

raptere

I'm currently just using Dot 4. I figured it was at least a small upgrade from Dot 3 and widely available. Sounds like if I ever got into actual track racing, I may need to switch to something more racing oriented, but since I'm currently only doing autox where the longest runs are maybe a minute, I would have thought Dot 4 would be sufficient, no?

The stuff in the reservoir looks maybe rust colored. Did I break some rust from the tubes free while flushing and/or doing much harder breaking than normal, and somehow it is flowing back into the reservoir?

Komet

I have also had that issue, I think it's rust coming out of the master cylinder. I don't think the fluid cycles enough to be from anywhere else. I guess you could try and smear the particles on a white piece of paper and let it dry to see what color it is.

raptere

Is it possible the Dot 4 fluid I switched to and flushed with is dissolving or dislodging more crud or rust that the old worn out Dot 3 fluid had been able to in the past years?

Should I be concerned at all, or just get it cleaned up as well as I can and don't worry about it... I actually finished the brake swap last night, which I had mentioned, and the new braking performance is pretty epic, so I'm inclined to see if I can suck as much of the debris out of the master cylinder as I can once it settles back to the bottom, but otherwise not worry about it too much...

raptere

Update on brake pedal feel after brake upgrade: maybe it was a result of flushing some more old fluid through the system, or doing a good old fashion two person bleeding job on the new front brakes, but my pedal while driving at least feels much firmer, and applies more braking pressure with the pedal in a higher position than before the upgrade. I still can't quite understand though that while sitting still, I am still able to push the pedal to the floor with the engine running. With the engine off, the pedal is hard as a rock. Is that how it is supposed to be???

QwkTrip

iTrader: (22)

Hard pedal without engine running is normal. Pedal is hard because there is no vacuum assist. Vacuum assist accounts for about 2/3 of the force pushing on the master cylinder. You lose that assisting force without engine running and feel the real heft of the pedal hydraulics.

raptere

Man I love it when there are hobbyist photographers at autox events!

raptere

Had another great autox event yesterday! Car performed really well I'd say, driver did alright...

A couple of people even commented how flat the car looked on the track, it really drives well! I guess a lot of people forget that these cars are born of IROC Racing.

I also just got around to replacing my front swaybar bushings before the event, that may have helped even more. I went with the blue moog ones which are advertised as thermoplastic. Still not totally certain if that is the same as polly or not, but the pickings are slim these days for such a large 36mm front sway bar. Most companies only offer up to a 34mm or maybe 35mm.

I'm continuing to experiment with per formate and feel related to tire pressure. I have beed running 36 psi front / 34 psi rear, and bleeding off access between each run as the tires warm up.

91banditt2

iTrader: (1)

Energy Suspension offers a 1 3/8" which is that works on a 36mm bar

raptere

I had tried this one that is a 1-3/8" (35mm) and it did not seem to fit right to me. https://a.co/d/5rpAotu]Energy Bushing[/url] Plus the bracket was wrong, the bolt holes on my car are offset, so the bushing ended up crooked. You also don't want the bushings too tight because it could cause drag on the bar while turning. It needs to move as freely as possible. The general profile of the bushing did not lend itself to fitting in the factory bracket with the offset holes either. The moog bushing seemed to fit much better, and was compatible with the factory offset bolt pattern bracket. https://a.co/d/gKarQ3U]Moog Blue Bushings[/url] No grease fitting, but I greased it up real well with super lube, and well see if it ever starts to squeak, its not hard to re-grease it...

raptere

I want to thank everyone that has given me feedback in this thread!

I really think I picked the most effective places to spend money on my car. I've now completed 6 or 7 AutoX events this summer, and the car is doing great. The most telling thing is that whenever people come with for a ride along, they are verbally surprised how flat and stable the car always seems to stay. I feel like the car really handles great, and maybe more importantly, very predictably. I've never lost it and spun all the way around, but maybe that means I'm just not pushing hard enough...

I did replace my rear rotors, calipers and pads with new factory parts, and put the same Hawk HP+ pads on the rear, so the braking is really pretty epic, I'm still learning how hard to stand on it for given speeds and turns, its quite easy to lock them up, even with my 275 width tires. The one performance addition I still need to complete is installing my front hub bearing spacers. I'm pretty sure the front hubs are set a little tight right now, so I think there could be some noticeable improvements by installing these, and getting the front wheels spinning more freely.

Whenever I'm talking with experienced AutoX'ers about my car at events, the one thing they all say I really need to do if I want to get to the next level is to go with 200 tread wear tires, that will be way more grippy that my current ultra high performance summer tires which are 360 tread wear. I am a little concerned if I do change the tires to 200 tread wear though, that the added grip could put so much load onto other suspension components it could possibly cause me to start breaking things. Is this a valid concern? Are their certain parts I should consider changing/upgrading before switching to truly grippy tires?

The only other thing that I would like to have is another 100-200 more HP... there are plenty of times I feel like I put the pedal to the floor, and feel like I could be putting more power to the ground. But, as long as I keep getting my a$$ handed to me by a bunch of 200 hp Miatas, I guess I just need to keep practicing!

IROCZman15

iTrader: (25)

sounds like you really are getting into it! I agree with where your train of thought is, and I will certainly suggest you DO go with a 200 treadwear tire. I went from a 300 treadwear Nitto 555 to a 200 treadwear Falken 660 tire and the results were ASTOUNDING! It takes a LOT of force to get them to break loose in a corner, unless they are dead cold. Once they get a little warm, its game on. Also, like you mentioned about not having had the chance to get the car to spin out or loop on itself, thats ok, but until you DO find the point where your car breaks traction, you wont know where the limit really is. I had a habit of always "looping" the car around during one of my final laps in several events. It was when i was really going for that "glory run" and sometimes the car would take it, sometimes it would spin out. After establishing that break-out point, I know how close I can get to it. Don't worry about everything breaking either, autocross isn't TOO violent on car parts when compared to some other types of car racing.

raptere

It just dawned on me that while I feel like I do push the limits of traction, it seems when I go over the limit, I under stear instead of oversteer and "loop" the car. Is this normal or common for these cars or is there some sort of balancing tweak I should consider?

QwkTrip

iTrader: (22)

Car will normally understeer (push the nose) unless you make some changes to the suspension. Oversteer can be scary as **** at high speed. Be careful what you ask for.

A lot of times people are inducing oversteer by trail braking into the corner. The car itself would probably understeer if they weren't braking. A car that always oversteers would be a disaster in the wrong hands.

raptere

Interesting, I do hold the brake a little longer if I want a bit more rotation into a turn, didn't realize that was trail braking, cool. Sounds like it's best to leave the car as it is and work on my driving!

raptere

Only one even left this first season of AutoX for me. It's been really awesome so far, and I can't wait till next year for more!

I actually won my division for the first time! Problem is it I was only me and one other guy in CAM-T, so no trophy or t-shirt... I did feel pretty good about it though he was running 200 treadwear tires, but he said it was only his second or third event, so I'm sure that's the only reason.

This had me contemplating if I was in the right division to be the most competitive for next year. Once I burn through my current 360 treadwear tires I'm definitely going to 200. Problem as I talked about earlier, since I have an aftermarket intake manifold, and have removed my cats, the lowest major class I can fit into would be ESP, but that allows full R spec tires, and I don't want to go there on this car, at least not yet. That only seems to leave me with CAM-T or possibly XS-A to fit into with my mods and requiring a 200+ treadwear tire. Does this sound right or am I missing some other option. Also, what really is the difference between CAM-T and XS-A as far as vehicle mod restrictions, they look largely the same, but I always seem to see mostly AWD cars in XS-A. There are more cars in the class thought than CAM-T, which seems like it would give me a better chance of placing as I improve...

Any thoughts on division? Or do I just stick with CAM-T? I want to have a class firmly in mind as I contemplate future mods, so I don't disqualify myself from an ideal class.

I'm also trying to understand if I ever get to the point where I want to go to nationals, did I read correctly that they do not have CAM or XS at nationals so I would have to race with the ESP cars?

z28cp

I haven't looked at the XS-x class rules, but I thought those vehicles were closer to stock than your car?
Regarding Solo Nationals, XS and CAM classes are run, they just aren't eligible for a jacket. In fact, the CAM classes are some of the larger classes at Nationals.

Beater79TA

Buy the 200TW tires. You won't stress anything enough to break it rapidly unless it was already failing. We ran close to 800 laps a year for a few years on 200TW tires and never broke suspension parts. SCCA Nationals is something you will either love or hate. I hate it. You get 3 runs per day for 2 days. So about 6 - 8 minutes on course driving. You get to work 2 hours per day chasing cones. In Lincoln Nebraska in early September.

raptere

Just completed my last AutoX even of the season. Going to be time to put her down for hibernation soon for the winter...

Race results were nothing to write home about...
Chicago Region SCCA TSSCC Event 9 - 10/23/2022

I think I was even able to figure out how to get my Track Addict app to render a video with all the data shown on screen using RaceRender 3.

It's been something like 7 or 8 events this year, and they have always been so fun, wet or dry! I've learned so much but feel like there is way more to learn.

This last even started feeling frustrating because I had a hard time getting my time to decrease much. over the last 4 runs (8 for the whole day) was only able to eak out another half second or so... If anyone has any feedback of any kind on the video of the run ahead, please share it. I am also not sure how fast my car should really go. As I have shared, the suspension is decent, brakes are pretty good, tires are basically garbage at 360 tread wear, and I only have probably 300 to 315 hp at the fly wheel...

I think I need to step back and evaluate all the variables I do have at my disposal and start documenting them a little more clearly and optimizing them.

Adjustments at my disposal:
Tire Pressure - The most recent pressure I have come to is 38 PSI in the front and 34 PSI in the rear. For my tires, I was just nearly wiping the calk all the way down to the end of the tread in the rears, but I seemed to still wiping away all the calk on the fronts, but since the car already understeers like crazy, I'm not sure more front tire pressure will help me, could it?
Front shock adjustment - I think two full turns harder from softest
Rear Shock adjustment - Quarter turn out from softest
fuel pressure with AFPR - I played with it a while ago and found slightly lower pressure gave better bottom end, and slightly high pressure allowed for slightly better top end, I don't remember how I left it... Suggestions.
Timing with distributor - I'll have to check but what timing is suggested on 93 octane premium?
Torque Converter Lockup via chip tuning - I believe I increased it slightly, but I have to check where it's set at. (Set to lock at 47, unlock at 44 for both high gears and low gears)

kestell123

From my time autocrossing my third gen I found that firming up the back and softening the front , with both the tire pressure and the shock settings helped to reduce under steer and get a little more rotation on tight courses. One thing I would note about your video, is that you seem to be leaving too much room between you and the cones. Some advice that I got was ' attack the back' , meaning to try to hit the cone with your back tire. As for tires , I loved the Bridgestone 71r's in 275-35-18.

DynoDave43

iTrader: (11)

Looks like another fun weekend. Makes me think I may be getting too old to do this, and I can't always keep track of where the track/ line is going, but still fun. I think I could run with the guy in the Tesla Plaid (not car-to-car, but driver-to-driver). Looks like he/she struggled some.

The only thing I noticed, and I'm judging just by audible exhaust note...it seemed like you were letting the throttle (and your speed) drop as you went through the slaloms. Try to establish a max speed you know you can run through there with...get to that speed at entry, and hold it steady all the way through. Don't accelerate, or let your speed drop...keep it smooth and steady.

If you are already doing that, then ignore my sage advice.

raptere

So, my engine just ticked over 150K miles. It's weeping a little bit from somewhere, I suspect either the oil pan or the rear main seal, both of which are hard to replace in our cars. Also, the fact that I am pushing this engine this hard with this many miles on the factory block, bearings, and rotating assembly, is making me nervous. I'm trying to plan out how to repair these issues, but if I have to remove the engine, or disconnect a lot, maybe it would be an ideal time to do the heads and cam I've always wanted to! That said, I'm looking at the individual component costs for everything I want to do, and it is adding up quickly. I then realized there are some pretty reasonably prices crate engines out there, so maybe that could be a better option???

I'm considering one of these two below, but how much power/torque can may '91Z handle with a factory 700R4 with a shift kit and corvette servo, and a factory 7.625" 10 bolt rear end, with reinforced cast aluminum cover handle??? Both of these looks like they have a pretty good power band around the auto crossing rpm range which for me is maybe 2000 to 5000 for the most part, with lots of low rev torque. In my head it would be nice to go with the 383 for the extra power/torque, especially down low, but will the car handle it? I would think the 350 may be a safer option, but I really do not know...

Also do you think these engines would play nice with my EFI intake and ECU??? I understand a tune will likely be needed, and I have chip burning equipment.

Chevy 350 Base Engine 390HP Crate Engine (high-performance-engines.com) $3,729.00


Chevy 383 Stroker Base Engine 415HP (high-performance-engines.com) $4,298.00

Komet

I think those engines would do pretty well with an HSR and a tune. With that torque output, they are threatening to install 4 neutrals in your 700R4 though.

raptere

Really? Both of them? Even the 390 HP 350 engine? Do i just then need to upgrade gearing in the trans? You think the 10 bolt rear should be ok?

I'm super torn because I do love my Camaro, but if this turns into too much of a project, I may just bank the cash and save up for a newer Z06... I regularly see them tearing it up at autox events, even in basically stock form! I know, it's blasphemy to say on this site...

Komet

I would say 420 lb/ft is in excess of what the 700R4 was designed to take in stock form and you should be prepared for the eventuality of a built trans or a swap to a more durable unit.

The 10 bolt probably won't explode if you aren't doing drag launches with slicks.

kestell123

A C5 ZO6 can be had for low to mid $20's and they are great cars. A c6 z06 will be high $30's to low $40's. I went from a highly moded 91 camaro {LS3, 6l80, Ford 8.8, big brakes all around, 15 way ajustable shocks and struts ect.] to a 2013 c6 Grand sport, both with good 200 tw tires and my times changed very little because I am still the limiting factor. I moved to the Corvette because I am getting to old to work on cars. If I had gotten the Corvette when I was younger I would have still turned it into a project, because like my wife said "You just can't leave things alone!! '" my point is the car is not holding you, back the driver is. If you enjoy working to improve the camaro, do that. If you want a car you can drive every day and just change tires to autocross, buy a C5 Z06. But if you still have the "just can't leave things alone" bug , Then the Z06 will turn into a 'Project" as well. Either way we are bless to be in car heaven, good luck.

QwkTrip

iTrader: (22)

kestell123 hit on what I think is an important subject matter when deciding what to do. You can get the newer car, you can go faster, and it will treat you better. The old car gives you a lot of projects though. You just don't tear into a newer car the way you can tear into these old cars and change them and modify them and whatever. Lots and lots of opportunities to tinker on old cars. If that kind of hobby is important to you then the older car is going to give you more of that kind of thing.

And the satisfaction of driving something you built? That's pretty neat if you ask me

QwkTrip

iTrader: (22)

Problem with these cars is absolutely nothing in the drivetrain can handle high power. Once you eclipse a certain point it's a total redo and it's basically the equivalent of an entire drivetrain swap. And when you have to upgrade everything then it's only natural to think to yourself, Why not go LS and electronic trans? Because you're going to be doing all the supporting mods anyway but the LS will make more power with better driving manners, and drop 100 lb (or more) off the front of your car.

This of course is without any regards for class rules.

QwkTrip

iTrader: (22)

Your stock components can take in the neighborhood of 400 HP. Results will vary.

raptere

It sounds like opinions are split... I'd say the 383 CI is basically out with the 415 hp and 475 tq, but its sounds like the 350 CI could be on the edge of tolerable with 390 hp and 425 tq... Does that sound right? Maybe I go with that one, and if the trans does fail, then I rebuild it with some beefier internals? Or replace with a built one. Its only a couple thousand bucks, right? lol!

I've got two young boys and a career that is taking more and more time. I do enjoy some of the tinkering, but I just don't have that much time to do them constantly these days, so there is certainly some logic behind considering something that is a little newer and would require less constant repairs... I am also a bit concerned about my specific car because it was driven year-round for much of its earlier life so if has a considerable amount of rust, floor pans, strut towers, other places, so it just makes me wonder if is a good idea investing too much more money into it, I just don't know if the rust should be a deal breaker or not. Are there places on these cars that rust can actually cause structural failures when the car is being pushed hard? I mean, the carpet padding is coming through in one place below the foot well of the drivers seat I'm pretty sure...

Decisions, Decisions...

Komet

Do you have a fuel system that supports 400hp? That would be another factor to consider. Personally I'd be doing a compression test and leakdown before tossing out your current engine for oil leaks. Speaking of oil leaks, is your pcv system intact?

raptere

And the dominoes begin to fall... LOL

What does it take to fuel 400 HP? I have a factory fuel pump, adjustable fuel pressure regulator, and factory I believe 22 lb/hr injectors, but those are not hard to change. Just another expenditure...

Quick search makes it look like the 390 HP crate engine would require a step up to 30 lb/hr injectors. Only $180 from Southbay, so that is not terrible, if the fuel pump will keep up with them...
Calculator (southbayfuelinjectors.com)
30LB BOSCH D3 CORVETTE CAMARO FIREBIRD TPI (southbayfuelinjectors.com)

Yes my PCV system is still intact. I'm not necessarily considering going crate because I think the old engine is junk. It's just the time and cost it would take to rebuild from the ground up, seems like it would equal or exceed that of the crate engine I am considering... The reality is I'll probably autox at least another season on this engine, so if you have separate ideas on the leak, or ways to verify, improve performance, I'd be all ears to those ideas too!

QwkTrip

iTrader: (22)

A Walbro 255 L/hr fuel pump is sufficient.

Keep in mind that 400 HP won't really be 400 HP. It'll be in the mid-300 at best once the accessory drive and exhaust is attached to engine, even less if you put TPI on it.

Advertised versus real world can have a huge gap.

QwkTrip

iTrader: (22)

Regarding 383 with TPI, I would suggest reaching out to people here who have done that. I think general feedback is they wouldn't do it again. The TPI intake won't let the engine rev so there is little net gain in actual power, just more low-end torque that is unusable (spins tires).

Torque (at tire) is what makes the car accelerate, but you only need so much torque before the tires can't manage it any more. High rpm engine torque is much easier to manage traction and wheel spin than low rpm torque, and will develop a lot more power and car will be astronomically faster. High Hp doesn't necessarily mean you have low torque, it just means you build more torque at higher rpm -- and that's what makes a car rip.

If you do a 383, I think you'll be waaaay happier ditching the TPI to gain more high rpm torque and power. The engine is big enough that you'll make enough low end torque anyway. That's the nice thing about bigger cube engines, they make torque by accident and you can focus on the higher rpm Hp for a really balanced package that drives and moves like stink.

And remember, gears multiply torque, so you could do something similar with a 350 and make your low end torque using numerically higher gears. Engine DOES NOT have to make gobs of low end torque, gears can do that for you.

raptere

Good point on gears, I assume you're referencing rear end gears. I have the 3.23 ratio in there now. I do still enjoy driving the car to work and what not though, so I don't want to have a crazy rear end gear where I'd be cruising at 3k+ rpm on the highway on the way to work... As it is I think I'm around 2000-2300 cruising on the highway at ~80 mph.

Regarding the intake it's not a stock TPI, I plan to re-use what I already have, a Holly Stealth Ram with dual 58mm throttle body, and 1-3/4" shorty SLP headers, so I'm pretty sure the engine would breathe nicely. Once the revs get up to 4-5k rpm, it pulls pretty well, even with my current factory cam and 1.6 roller rockers. I frankly would have expected my car to match or exceed their power levels at the crank of course since their dyno testing is all done with carbureted intakes, I'm pretty sure... As long as it is properly fueled and tuned.

I know I'm kind of making up for having an auto trans, but my issue is when I come out of turns and put the pedal down, I'm out of my power band, so it takes a second or two before I really feel the power coming up and by then it's usually time to brake again, that's why I'm thinking I need more power down low. While thinking about it, would just upping to a higher stall torque converter improve or solve that problem? If so what stall should I consider? What even is stock?

This is also all planning for my future planned 200 tread ware tires, so I'm under the impression those are pretty grippy and can put a decent amount of power down even at low speeds.