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For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

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Old 04-10-2010, 08:35 AM
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For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Just got done dynoing my 85 Iroc Z28 305 TPI, pull 210 rwhp and 259 rwtq. (wanted a baseline before I started my top end build up) Save for K&N drop in air filters, and a slightly hotter in cap coil, this thing is stock right now with 33K miles. Is this for real? SAE correction had it at 205 rwhp. Was chevy really underrating this motor that much? Tech date on this board has it at 215 at the flywheel which i would think that rear wheel would have been closer to 180-185rwhp. I'm debating with myself on doing another pull in town on a different dyno to verify the results.
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Old 04-10-2010, 11:28 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

The factory would usually publish a conservative number that they could all but guaranty that each engine would produce. Some would be better, some worse, but the conservative average was often a little higher than the conservative minimum.

The same people rated the 231 Buick in the TTA at "250HP" and we all know how accurate that was.
Old 04-11-2010, 02:56 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

IIRC they used a better cam in the 305 in 85.86 they dropped the power off with a smaller cam.
Old 04-11-2010, 06:23 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Kewl, i won't waist the money on a "second opinion" pull then. I'm hoping to get close to 280 - 300 rwhp out of it when I'm done with the top end overhaul then...i know a lot of people say its a waist to spend money on the 305, put because of the mileage and condition the car is in, i'm trying to keep it somewhat close to original. Otherwise I'd probably just rip the 305 out and drop in an LS2 and be done.
Old 04-11-2010, 07:37 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

what all are you planning to do to it? You have stock exhaust too?
Old 04-26-2010, 10:58 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Everything stock for these pulls including exhaust save for drop in K&N and a hotter in cap coil.

Plans:
Converting the 85 MAF setup to a 90-91 MAP setup (rewiring in progress as I type this)
CAM: SK12-208-2 (@.050 i:211 E:221 Lift: I.442" E.465" LSA110)
SLP Intake runners
30lb injectors
52MM Throttle body
Trick Flow 175cc Aluminum Head (TFS-30300003)
Edelbrock headers
High flow cat

I really am avoiding the exhaust behind the cat because I reallllly like the sound the motor has now, although i'm sure the cam will change it somewhat. Thoughts? really don't want to get any louder here.

So nothing crazy here i think. Trying to stay true to the original TPI setup for the car, just trying to make it better. I think 300 rwhp will be a push with the stock bottom end in the motor since RPMs will be capped, but I don't want to make the car unlivable either. The car is in excellent condition inside and out with only 34K miles on it and its been garaged all its life, so I don't want to tear it up.
Old 04-26-2010, 11:17 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Nice, so it's nearly as powerful as my SAAB.
Old 04-26-2010, 11:29 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by Saabster
Nice, so it's nearly as powerful as my SAAB.
lol, 85 tech here... My wifes 2003 minivan with the 3.5L VTEC makes more hp right now (although doesn't have the torque), hence the want for some work to wake up the 305.
Old 04-26-2010, 11:35 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

I know, I'm just messin. Good luck dude.
Old 04-26-2010, 11:48 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by Saabster
I know, I'm just messin. Good luck dude.
thanks man! Photos of progress i think I can share out.
Old 04-26-2010, 11:58 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

those 30lbs injectors sound huge for that engine. stock is 19, going to 30 is almost a 60% increase. 22 or 24 should cover it without hurting your idle
Old 04-26-2010, 01:42 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by darkhorse91
those 30lbs injectors sound huge for that engine. stock is 19, going to 30 is almost a 60% increase. 22 or 24 should cover it without hurting your idle
Thanks for the info...the guys that I was working with was recommending 26 or 28lb injectors with the entire setup, and the 28s were really expensive, so we subbed 30is in...

But it sounds like maybe ecm won't cycles to run the 30's though in low flow situations and will hurt idle and low throttle situations then?

Definitely want to do this right the first go round, open to all advice...

thanks!
Old 04-26-2010, 10:58 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Somewhat relevant story: When I was in school for aircraft maintenance, one of the instructors told us about an aeroplane (probably a Cessna) that was sold and drastically outperformed all of its ratings... faster rate of climb, higher cruise speed, lower fuel consumption, etc. They pulled the engine, thinking for sure it was the wrong one, and upon teardown found that it just happened to be perfectly blueprinted, from the factory, as a total fluke. Every internal measurement was within ±0.0005", when allowable tolerances were more like ±0.003". The engine dyno'ed something like 50 horsepower above its rating.

Just goes to show, a well-built engine is a definite advantage, although if you're doing a rebuild there's lots of much cheaper horsepower to find elsewhere before you think about blueprinting.
Old 04-27-2010, 01:48 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

I'm assuming yours is a TPI 305 then?

I with my damn (92!)TBI 305 could get make it to 200ish rwhp
Old 04-27-2010, 02:59 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Man, I bet the little tykes car has more go than your car! jkjk

Quite a nice looking car. I don't blame you for wanting to keep it original, or close to when it's in that kind of condition.


Honestly though, if you're looking for 300 numbers, a well made exhaust and a good pair of flowing headers should help. I know you like the current exhaust sound, but something you gotta consider is, sometimes a lil bit of sound has to be sacrificed to make any +hp gains.
Old 04-27-2010, 04:59 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by Samurai_Of_Dawn
I know you like the current exhaust sound, but something you gotta consider is, sometimes a lil bit of sound has to be sacrificed to make any +hp gains.
Not anywhere near true....

Here's a 2001 Mustang GT Procharged and intercooled at 9 PSI. If his engine is stock, I'd guesstimate that he's making 350-370 RWHP. Guess what? Stock exhaust!

http://www.youtube.com/watch?v=ZPmYG8h1yzA

High flow cats, headers, freer flowing mufflers, they all free up a few horsepower here and there, and even allow the heads to run cooler in come cases, but it's really not needed to make big amounts of power.

Roush's 2010 "sleeper" Mustang makes over 400 Horsepower, and has an exhaust that was made for the GT. The 2010 Camaro is also another car with 400+ Horsepower and a stock exhaust system, the slightly restrictive stock exhaust system.

Heck, I love loud cars though. Check my Car Domain link in my signature.. On the "Engine" page below the couple pictures of the engine I have a few exhaust videos. High revs, idle, and a video of me holding it around a constant 2,000-2,500 RPM. Long tube headers, 3 inch Y pipe, no muffler. I hacked off my Flowmaster 40 series.

I'd love to pick up some Borla Stingers and have a custom true dual system made though. It'd sound awesome in my opinion. I love Stingers and SLP LM1's, or any type of bullet muffler and/or resonator type muffler. I have the absolute loudest car in my town, and most likely one of the top 10 loudest cars in all of Sussex County Delaware, but, even with my 350, I'm not making over 250 RWHP.
Old 04-27-2010, 09:33 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by Shadow Z
High flow cats, headers, freer flowing mufflers, they all free up a few horsepower here and there, and even allow the heads to run cooler in come cases, but it's really not needed to make big amounts of power.
I'm with you that 99% of people don't need as big of an exhaust as they think. My SAAB is a 2.3 turbo that makes 235whp through two cats, two muffles and 2.5" piping from turbo to tail. A 3" exhaust is really plenty for anything sub 500 hp. However, what applies to the mustang doesn't necessarily apply to us. The headers and y-pipe are known restrictions on these cars.

Also, big does not equal loud and vice versa. My completely stock RS makes a lot of noise, cause the exhaust has rusted away just before the muffler. If you want quiet, Magnaflow makes excellent straight through mufflers that offer little to no restriction.

Personally, I'm looking at a Flowmaster catback cause they're one of the few that make a single exit catback (twin tips from a single pipe are retarded). I don't like the way Flowmasters sound though so I'm probably going to dump the muffler for a Magnaflow. If it's still too loud I'll pop a resonator in the middle just to calm things down.
Old 04-27-2010, 12:57 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Hmmmm, the barometric pressure on the dyno weather station is reading around 29.05in-hg. Average at sea level is 29.92in-hg. Just wondering at what altitude the dyno run was taken at?
Old 04-27-2010, 02:46 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

That mustang is obnoxiously loud, bleh!
Old 04-28-2010, 06:06 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by Shadow Z
Not anywhere near true....

Here's a 2001 Mustang GT Procharged and intercooled at 9 PSI. If his engine is stock, I'd guesstimate that he's making 350-370 RWHP. Guess what? Stock exhaust!

http://www.youtube.com/watch?v=ZPmYG8h1yzA

High flow cats, headers, freer flowing mufflers, they all free up a few horsepower here and there, and even allow the heads to run cooler in come cases, but it's really not needed to make big amounts of power.

Roush's 2010 "sleeper" Mustang makes over 400 Horsepower, and has an exhaust that was made for the GT. The 2010 Camaro is also another car with 400+ Horsepower and a stock exhaust system, the slightly restrictive stock exhaust system.

Heck, I love loud cars though. Check my Car Domain link in my signature.. On the "Engine" page below the couple pictures of the engine I have a few exhaust videos. High revs, idle, and a video of me holding it around a constant 2,000-2,500 RPM. Long tube headers, 3 inch Y pipe, no muffler. I hacked off my Flowmaster 40 series.

I'd love to pick up some Borla Stingers and have a custom true dual system made though. It'd sound awesome in my opinion. I love Stingers and SLP LM1's, or any type of bullet muffler and/or resonator type muffler. I have the absolute loudest car in my town, and most likely one of the top 10 loudest cars in all of Sussex County Delaware, but, even with my 350, I'm not making over 250 RWHP.


Yeah, but something to consider is the procharged mustang has a supercharger giving him a nice ammount of hp the owner is pleasant with. Hmmm come to think of it, did the poster of the topic want a sleeper car?

I was thinking of the fact of how restrictive the stock 3rd gen camaros exhausts are compared to a custom made one. They do benefit from them correct? I suggested a custom exhaust mainly because it's another proven +hp stepping stone. If he wants to stick with a stock exhaust, by all means, whatever he says goes. It's his car. I just threw out a suggestion. Would updating the piping with better steel (same size/diameter) make a big impact on sound?

As for the stock exhausts on newer vehicles, something you gotta consider on them is they are made of a far better material and craftsmansship than our cars in their time plain and simple.
Old 05-06-2010, 10:42 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by 1989GTATransAm
Hmmmm, the barometric pressure on the dyno weather station is reading around 29.05in-hg. Average at sea level is 29.92in-hg. Just wondering at what altitude the dyno run was taken at?
We are at ~900 - 970 ft above sea level.
Old 05-06-2010, 11:11 AM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Here is the youtube video of the dyno pull...

I like the sound, but may go ahead with a high flow cat and a flow master setup...a buddy's dad owns a muffler shop and has a cat back set up taking up space right now.

I'm regretting the purchase of the edelbrock headers, i'll have to take and post a picture how they combined each cylinder together into the collector, looks VERY restrictive to me. I guess as long as they are better than stock cast iron manifolds, they'll be OK.

I still have to get past the rewiring which is taking FOREVER! Especially now that I'm back on the road again for work and don't have the evenings to work on it.
Old 08-03-2010, 01:37 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

You don't need injectors that big!!!!!!! holy cow! You would probably run faster on stock 19 lb and an AFPR set between 46 to 50 psi. Or, stock fuel pressure with 24 lbers. That is the biggest I would go until I hit about 350 hp or more! Seriously
Old 08-03-2010, 01:40 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Do not avoid putting a catback on your car.LOL. Yeah, it may sound good, but you will run FASTER on the street with a full exhaust. Our cars LOVE backpressure. You will make a ton more low end torque on the street with a nice catback exhaust. It probably would sound better too if you got the right muffler.
Old 08-03-2010, 01:43 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Your heads and cam sound like a good match on that motor though. What gear ratio are you running? If you have an auto car and with your setup , I would not go above a 342 gear. You would probably run the best with a 323. (keep you in your powerband longer). If i were you , i would be looking into my gears and a shift kit for the tranny. Possibly a 2200 stall too. Let me know how it goes. Do yourself a favor and advance your timing to 8-10 degrees BTC and get and AFPR and kick up the pressure a few pounds first.
Old 08-05-2010, 04:08 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

man idk if i would tear into an iroc thats in that good of shape and having such low milage....you could easily pick up another one cheap and have fun with it lol. but thats just me talkin lol.

now i do find 210 whp impressive for a STOCK iroc. my 86 iroc (and yes i know the cams were changed in 86) but mine was rated 190hp and like 285tq at the flywheel, not wheels. now i put shorty headers, full 3" exhaust, slp cold air, tb coolant bypass, jet air foil...then i went to get an A/F ratio tune on the dyno. all he did was litterally change A/F ratio and nothing else. and all i got out of it was like 185whp and 283wtq. with the 25-30% slippage taken out, it produced 233hp and 362tq at the flywheel. now thats more power than the l98 350 tpi produced stock at the flywheel lol. so thats the only thing i was impressed with. now im even more impressed with how you managed 210whp on a stock engine. was yours a manual tranny or auto??

now for your goal of reaching 300 WHEELhp with those very minor upgrades sounds impossible. and yes 30lb injectors are WAYYY to much for that. i pulled out my lb9 and did a 383hsr project. it pulled 312whp and 400wtq.....my signature has mods listed for it. now seeing a mild modded 305 do that just doesnt seem possible man.
Old 08-05-2010, 10:09 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

That is not true. Stock L98 made 245hp/330 ft lbs@3200 rpm! With some bolt ons , you are running about 275hp or so easily.
Old 08-05-2010, 10:12 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

If you wanna break 300hp, you need to start with heads.
Old 08-12-2010, 11:07 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
If you wanna break 300hp, you need to start with heads.


just got back the trick flo heads from a buddy, new springs set up on them that won't destroy the tappet cam. The original dual springs are going to another guys 406 buildup: he had a beehive spring snap on him the first time he revved past 4 grand so he get to rework the heads and a piston top .

I read a recent article in superchevy that they pushed a 305 to 362hp with these heads...they said the exhaust ports on the outflow the factory heads intake ports. http://www.superchevy.com/technical/...et_system.html
Granted, the tappets are going to hold me back, as is the TPI and lack of RPM (i won't push past 5500), but I'm hoping the siamesed intake runners and porting out the plenum helps offset some of the TPI penalties.

Now i need to track down a cheap tpi intake set up so I can port everything to match off the motor.

As for the injectors, now that I've been doing my own tuning and have somewhat of a clue what I am doing, YES, i will be trading my injectors in for smaller ones, probably 24lb for now. (any takers?)

The one thing I have picked up now that I have the new ECU installed is some milleage, i've picked up from 17ish mpgs combined to 19mpg combined, not bad. Motor is much more throttle responsive now as well, especially through the rev ranges now that it is tuned. I have to wonder if its a combination of converting to the map setup and the newer ecu is just plain faster than then 85 ecu, keeping up more accurate timing with the motor.

With the 85 ecu, I could spin the tires though first, but as soon as second hit the burnout was done. With the new ECU, i can hold second almost indefinitely. (had to try it once!, got great logging data out of it from my moates box when doing it, i'll have to post my excel macros once i get them perfected for colorizing and filtering the csv data exported from tunerpro to make looking for bad BLMs and wideband readings.)

So I really can't wait for it to cool off and finish this project! For now, cars been parked: Dark interior + over 100 degree days + no A/C means = i ain't driving it! Non A/C 'd garage means I ain't werkin on it either! ugh!

Last edited by iridium130m; 08-12-2010 at 11:10 PM. Reason: typos
Old 08-12-2010, 11:15 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

ha, just imagine how much MORE responsive it will be after going down to the proper injector size!

Last edited by ninetyone; 08-12-2010 at 11:18 PM.
Old 08-12-2010, 11:18 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Hell if you are running a 305 motor, you should be ok with the stock 19 lbers or at the most the 22 lb 350 injectors.
Old 08-12-2010, 11:25 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
Our cars LOVE backpressure.


I've seen you give a lot of BS info, but this tops it all.. No engine LOVES backpressure. Even two strokes, which are made to run far more efficient due to the effects of backpressure in the expansion chamber, HATE backpressure! Backpressure makes the engine work harder, to PUSH THEM EXHAUST GASSES AWAY from the exhaust valves, and out through the exhaust system.

Go buy a gun, weld the barrel shut, shoot it, and then see how much that gun likes backpressure. Works the same way with an exhaust system. Go put your hand over top of the exhaust of a very small (25-100 CC) engine, hold it tight, and watch how quickly that thing stalls. That right there, is backpressure.

What will cause power gains in exhaust related modifications, is increased velocity. On a stock 305, I'd bet that you could run a straight (cat-less, muffler-less) 2" exhaust, and make more power compared to a 2.5" system with cats, and mufflers. Why? A smaller diameter, and less restrictions, will help speed up the velocity of the exhaust gasses. Therefore, making the engine "press" a lot less to make the exhaust gasses exit.

Again, this can easily be compared to a gun. If you're not familiar with the sport of paintballing, the typical paintball is .68 caliber. Now, strap a 110 millimeter tank cannon onto that, and what will happen? The CO2 would flow right around the paintball, doing absolutely nothing towards moving it. It's all about creating a high exhaust velocity, and backpressure completely hinders that. Try to remember that.
Old 08-13-2010, 09:17 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
Hell if you are running a 305 motor, you should be ok with the stock 19 lbers or at the most the 22 lb 350 injectors.
still on stock 19's as the only work done so far is the ECU swap and complete engine harness rewire. I do have to get rid of them though as they leak like crazy.

Do have question though...anybody know where i can get a new one of those Square rubber/plastic/foam/hotglue wiring harness seals for the passenger kick well passthrough?

Note sure if I posted rewire work, here it is.

Come on fall, get here soon so I can get the engine work done!
Attached Thumbnails For real???  Stock 85 Iroc Z28 305 pulls 210 rwhp-rewireing.jpg   For real???  Stock 85 Iroc Z28 305 pulls 210 rwhp-rewiringdone.jpg  

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Old 08-16-2010, 06:43 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

why 30 lb injectors? that is way toooo big! 24 will be more than enough. you can always use an afpr later on.
Old 08-16-2010, 06:46 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

gee that's funny, i picked up a lot more low end torque when i added a catback instead of the straight pipe i had ouy of the converter.
Old 08-16-2010, 07:22 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
gee that's funny, i picked up a lot more low end torque when i added a catback instead of the straight pipe i had ouy of the converter.
In the butt dyno, right? Yeah...... Do you have a huge amount of extensive testing, to back this up? Did you go to the track, and run at least 10-15 times, average them numbers, before AND after the catback install?

What that catback did for you was increase your EXHAUST VELOCITY. Increasing backpressure doesn't do **** for you except for rob power. Again, think of gun barrels. Which guns have the highest velocity? In other words, highest FPS rating. The .223 SS Magnums.. 4,000+ FPS. What are they shot from? .223 rifles! What do they almost always have? 18"+ barrels!

Length, and diamter play absolutely major roles in creating a high exhaust velocity, which equals more power. Why do you think BBK makes a dual stage intake manifold for the 2 valve 4.6 Mustangs? Why did a LOT of stock Lincolns have the variable length intake manifolds? Simple. Increased intake velocity. The Ford 4.6 obviously isn't a large engine, so they need to constantly maintain a high intake/exhaust velocity, to be efficient as possible.

Long, narrow intake runners create a high intake velocity lower in the RPM range, and the switch to short, wide intake runners allow the engine to breath better higher in the RPM range, due to that higher velocity throughout.

Your backpressure BS is hilarious. You do not even have the slightest grasp on the concept of exhaust scavenging. Like I've probably mentioned before, go shove a potato in your tail pipe, head over to a dyno shop, and just see for yourself how much more power you make. Oh.. Your engine would not even run at that point. Huh, wonder why. Maybe because of that BACKPRESSURE?

I just do not even understand how one can be this clueless. What part of killing the kinetic energy of your internals, due to making them struggle to shove exhaust gasses out, increases Torque? When you're on the highway cruising, and you take your foot off of the gas, why do you not stop instantly? Kinetic energy! Basically stored energy, due to the motion of an object. Ever heard of weighted flywheels? A lot of 4 cylinder, and overall less powerful vehicles will use stock, or weighted flywheels in drag racing. It allows them to store energy in that flywheel, and get a good launch while not redlining the vehicle, since redlining at 8,000+, then dumping the clutch on any 4 banger would cause even slicks to lose traction.

That same concept of kinetic energy applies to the internals of an engine. When you are going down the road, and let off of the throttle, the stored kinetic energy of your 3,000+ pound car keeps the engine momentarily spinning above idle, until you obviously slow down. What you're doing by adding backpressure to an exhaust system, is killing that kinetic energy.

I'll put this in re-re terms. Make a fist, and continuously move your arm forward and back, in the air. Now go find a trampoline, or something flexible, and see for yourself that it is harder to push your arm completely forward, when although flexible and will move, something is in your way. That is the only way I can think of, of how to simulate exhaust backpressure for you.

Seriously, you need to read up on this.

http://www.tercelreference.com/terce...st_theory.html

And this.

http://www.nsxprime.com/FAQ/Miscella...austtheory.htm

Then again, I would expect this stuff from someone who claims that performance-oriented long tube headers will slow you down when compared to stock manifolds. Someone who claims that their buddy's stock internal 305 can pull wheelies on the highway at 55 MPH, and that, that same 11 second car requires a parachute, when don't quote me, but I believe parachutes are required at 9.99 and below, and/or 150 MPH and over. At least when going by NHRA rules. Most local tracks you'll find are much more strict.
Old 08-16-2010, 07:58 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

my car made more power down low with a catback. I had a hard time keeping up with traffic with no catback. Car was only good for WOT runs then.LOL

Last edited by ninetyone; 08-16-2010 at 08:15 PM.
Old 08-16-2010, 07:59 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Again our car's are better suited for lowend torque.
Old 08-16-2010, 08:04 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

It is not that long tubes slow you down,but you will notice a big,big decrease in low end torque,thus everything else about the car will have to be changed like intake ,rear etc to take advantage of the increased torque up top
Old 08-16-2010, 08:12 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Coming out of the converter? A straight pipe, out of the converter? Do you understand anything at all? A straight pipe is headers, and just that, a straight pipe. Nothing but pipe. No muffler, no catalytic converter.

Sure, it will give you more backpressure, but backpressure will NOT give you that extra torque. What will give you that extra torque down low is that increased exhaust velocity. Adding a full exhaust system is just like adding a longer barrel to a gun.

Get it? Do I get it? Look at the BS that you're saying. I know how to design an efficient exhaust system, depending on the application. BACKPRESSURE WILL NOT, AND I REPEAT, WILL NOT GIVE YOU MORE TORQUE. Backpressure KILLS that torque, due to the loss of kinetic energy, by making the piston push harder to make the exhaust gasses exit the valve, and follow throught the exhaust system.

I honestly do not know where you're getting this "backpressure gives you torque" BS. You remind me of the Youtube mechanics. Guys who will get on Youtube, watch a video of a 700 Horsepower Supra autocrossing, and tell them to dial down the boost when exiting a corner, as if they do not know what they're doing.

Or, gotta love these guys. The Youtube mechanics who complain when someone bounces off of the limiter a few times, when the whole reason that limiter is there, is to hinder the engine from over-revving, or in simple terms, causing damage.

Backpressure does not create Torque. I don't know what else I can say to explain this to you, it just does not happen. Backpressure robs the internals of that kinetic energy that they have built up.

Honestly, how old are you? Around 14? I know there's one member on here who's 13, and basically got his IROC handed down to him from his mom, but even he is a bit smarter than you. This is literally making me sit here and laugh to even be debating this crap. Especially with someone who cannot even get their gear ratios down. What is a 2:73 gear ratio? What would you have to do to get that thing to even hit 1 MPH with a stock transmission, and tires? Rev to 30,000 RPM?

I think you meant 2.73:1. Ah, but I'll be incorrect there too. Just as backpressure gives you more power, long tube headers don't perform as well as factory stock iron manifolds, 3.73:1 and 4.10: gears make TPI cars slower, 11 second cars need parachutes, stock internal 305's can wheelie on the highway at 55 MPH, right?

How many explanations would it take, to make you grasp the simple idea that backpressure does not create Torque? An exhaust system is basically a trade-off. A small diameter exhaust will keep the gasses hot, and moving fast, yet that smaller diamter will create a bit of backpressure, which is BAD. Large diamter exhausts on a stock 305/350 would cause the gasses to cool far too rapidly, and flow slowly, despite having nearly 0 backpressure. You choose.

Wait no, in your tiny mind, backpressure creates torque! Oh yeah, and you think it's BAD to raise your factory powerband! No cams, no headers, no 3.73:1 or 4.10:1 gears, nothing! All stock!

Wow.. That is all I can say.
Old 08-16-2010, 08:17 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
It is not that long tubes slow you down,but you will notice a big,big decrease in low end torque,thus everything else about the car will have to be changed like intake ,rear etc to take advantage of the increased torque up top
Oh really? Is that why my bolt-on 350 with a 100% stock 700R4, with the sluggish 100% stock converter, would spin the tires at only half throttle for a short distance, from a stop? I have long tube headers! Looks like I didn't lose any low end Torque!

Keep in mind that 305's and 350's have the same stroke, 3.48. I have MAYBE 50 FT-LBS more than a stock LB9. My 350 is a 2 piece rear from an earlier Suburban, rated at 200-210 HP stock, and 300 FT-LBS. Basically the same power levels as the LB9 when stock.

Yeah, them long tubes really robbed me of a lot of low end torque! It's all in my imagination that I can stomp on it from idle, get great throttle response, and spin the tires.
Old 08-16-2010, 08:24 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

A 373 ratio in a TPI car will throw you out of your usable powerband. Unless you change everything else so that car lives in the upper rpm range. Let me see, you would need an intake like a holley stealth ram, cam, might as well get heads first to make some real power, then maybe longtubes. Not to mention reflash of the ecm. My tpi car will still take your 86.
Old 08-16-2010, 08:25 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
Again our car's are better suited for lowend torque.
I'm glad I don't share a car with you then, or it will always be slow.

Launch soft, shift slow, rev low, stay slow! Even 5.9 Cummins diesels, which are very finely suited for operaton from idle, where they make nearly peak torque, to 2,000 RPM's, are at the drag strips running 4K RPM+!

Why, you ask?!

Horsepower = Torque X Engine RPM / 5,252.

You keep right on thinking that a low revving car is better, and you'll STAY SLOW. The key to being fast is making a **** load of Torque, and carrying it as high into the RPM range as you can. That is what will make you gobs a power.
Old 08-16-2010, 08:28 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

I guarantee you are making torque much higher in the powerband than you did before. You might have made 345 ft@3200. Then after header install made 360ft but not until around 3800rpm or higher.
Old 08-16-2010, 08:32 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

wanna race?LOL
Old 08-16-2010, 08:36 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
I guarantee you are making torque much higher in the powerband than you did before. You might have made 345 ft@3200. Then after header install made 360ft but not until around 3800rpm or higher.
Well hey, you know what? I'm perfectly fine with that!

345 FT-LBS at 3,200 RPM = 210.2 Horsepower!

360 FT-LBS at 3,800 RPM = 260.5 Horsepower!

Do you see what's happening there? An example, although unrealistic, that YOU gave, contradicts everything that you've said before.

WHY the hell would I want a measly 210 Horsepower down low, when up top, I could have 50+ more Horsepower? 3,500+ RPM, is where I'd be revving at the track. Have you ever gone to a drag strip, and kept it under 3,200, just for the SUPERIOR FEELING of that low end torque? Have you, honestly?

You're not making a bit of sense right now. I'm very tempted to call up a few local engine builders, and explain this situation to them. Guaranteed any professional engine builder would tell you what I'm telling you. The key to making power, and being fast, is making as much Torque as possible, and carrying that up as high as you can into the RPM range.

Not taking a factory car, leaving the stock manifolds on, stock gears, and expecting to be fast, just because you make a decent amount of Torque down low. That's a bunch of BS.
Old 08-16-2010, 08:40 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Maybe if you want a track car. I like a stop light car.
Old 08-16-2010, 08:40 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

This coming winter/spring I will if you want, in an equally slow car. I bent a rod or two in my IROC, so I've decided to buy a "new" car while it sits. New to me, anyway. An '01-'04 Mustang.

They make 260 HP and 302 FT-LBS of Torque. Very similar ratings, compared to a TPI car. I decided to let the IROC sit in the garage for a while, just because I don't want to depend on an 80's car with 99,000 miles anymore.

Which county do you live in? I'll gladly race a few months from now. I'm in Sussex.
Old 08-16-2010, 08:45 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

I guarantee that going with 170 /60cc heads and no bigger, a stock cam, stock gearing and a ported only stock intake will be faster and CHEAPER than a high rpm build
Old 08-16-2010, 08:45 PM
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Re: For real??? Stock 85 Iroc Z28 305 pulls 210 rwhp

Originally Posted by ninetyone
Maybe if you want a track car. I like a stop light car.
Thank you for proving my point even futher. A good "stop light racing" car is going to be a car with most likely 4.10's, and in the case of an automatic, a higher stall Torque converter. With any kind of car that's meant to accelerate from 0-60 as fast as possible, you don't want low end Torque, you want that thing to get up and jump into the powerband as quick as possible, without burning the tires off.

When I think of low end Torque, I think of an M35A2 "Deuce and a half". They have 330 FT-LBS of Torque, 6.72:1 diffs, and weigh 13,500 pounds. With all of that low end torque, they can hit an absolute top speed of 56 MPH, with a safe cruising speed of 48 MPH! Yeeeeehaw! Hooray for low end torque!


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