Ok i have A 1987 Iroc-z28, 5.7. Magnaflow Exhaust, shorty Hooker headers 2055. Gutted My airbox and made custom ones to redirect all the air to the throttle body. Sounds Like A BEAST! no performance chip YET. but im going to Get a dyno test and i just want 2 know how much you think it makes before hand.............. OR

 

2

 

I had basically same mods and I would guess 225-230whp. Enough to run 13.6 at 97mph with 2800 stall on slicks.

 

Interesting. I was going to say 235rwhp.

 

Aww man Realy??? i thought It would be faster....how would i make over 300 rwhp? WHen it was stock it supposedly made 220 Hp or so. thats dissapointing if true....We'll see on the dyno

 

You've opened up the exhaust, but if you really want to feel a difference you need some real mods like a set of heads and a cam. And of course, everything that goes with them.

 

An easy way to feel a huge difference is playing around with the gearing. Porting your heads and intake will make a big difference as well. Having your car tuned at the dyno will help a lot as well. Other than minor mods to reduce friction and windage losses, thats about all you can do short of a cam swap.

 

Im Kind Of Lost???...what does 'porting your heads mean'?

 

Porting is the process of removing material where necessary (in and around the intake and exhaust ports) to increase the airflow potential of the cylinder heads and intake manifold you already own. Basically, you open up the runners as much as possible and smooth the edges the best you can so more air moves more freely into the combustion chamber. Have your engine tuned after doing this in order to correct your fuel map for the increase air flow. Now you got more air and more fuel, which will produce more power.

 

Ooooh Alrighty Then....Have you guys heard of those siameze intake runners??? they are supposed to be more bigger and wider to allow more air...any thoughts.....

 

Yup. Won't make more power without supporting mods though... head and cam swap would be the biggest improvement short of nitrous or boost

 

210 - 220 hp at the wheels

 

The stock hp/tq numbers are rated @ the crankshaft. When you measure @ the wheels, the number you see will be (roughly) 15% lower than the crank measurement (some say you will loose a little more, some say a little less) if you have a manual transmission, and even more loss @ the wheels if you have an automatic.
So, If your car makes 220 at the crank, and has a manual trans, it is going to only show to be around 185-190 at the wheels. (220 x .85 = 187)

To make 235 rwhp (235 x 1.15 = 270 hp) you would need to be making around 270hp @ the crank. So 235 RWHP is actually about 50 more hp than 220 CRANKSHAFT hp. Does that make sense? It's two different measurements...
300 rwhp would be around 345-350 crank hp, again, with the manual trans. To make 300 rwhp with an automatic, you would need to be making even more than 350 at the crankshaft because the auto eats up more of your hp before it gets to the wheels ....
Of course this method of estimating drivetrain and parasitic power loss is just that, an estimation. There are several different theories as to what percentages these calculations should use, or if the hp loss is even actually a percentage, or if the amount of loss is a fixed amount depending on the combination of parts being measured......It just depends upon whom you ask.

 

Alright cool, im starting to learn more and more lol. thanx guys for all your help..... . so even with the hooker headers and magnaflow exhaust replacing the stock parts...that would only help a bit.?? i mean, dnt get me wrong,,,i love the fact that my car sounds like a monster but when it sounds better than it performs....i'd rather have it even out u knw what i mean fellas. and whats this head and cam swap??

 

Lets say you were at 220HP to begin with. You add headers and a full exhaust and that would put you close to 250 or so. You probably wouldn't gain any more than 30HP with your exhaust. You also gained a bunch of torque across the RPM range with your exhaust upgrade. I'm running around 200HP and it sounds like a monster too when I hit the pedal, but that doesn't mean its fast!

 

And then, there is the difference in PEAK TQ/HP, and AVERAGE TQ/HP......Headers may only increase output by 15 PEAK HP, but it may make much more of a difference in AVERAGE HP. AVERAGE HP/TQ is what you need to have more of for a street driven car to be quicker/faster....

 

Heads swap is simply swapping your cylinder heads for a better flowing pair. The new ones will flow even better after porting and polishing. Changing your camshaft will have the biggest effect overall. Your camshaft is what decides when and how your intake and exhaust valves open.... way to much to explain here. Basically, better flowing heads with a MATCHING camshaft will significantly change the way your engine performs.

 

Alright Cool!! THANX. im going to get to work on all those things. i have some money to play with and i will b posting pictures 4 evryone

 

I agree...

 

get some long tube headers instead of shorties

 

stock 4th gen LT1's with auto tranny were around 235 RWHP. They were rated at 275 FWHP so maybe that will help you? I'd guesstimate you somewhere around 200RWHP if you have an auto tranny. The number to really want is torque because that is at lower rpm's and what you feel around town. Who cares what you make for HP spinning at 5200 rpms ?

 

stock 4th gen LT1's???

 

yes

when you read specs they are rated at flywheel HP. Also, the f bodies in 4th gen were rated on regular gas while the vettes used premium and had a better flowing exhaust and intake. So, you take an LT1, get it tuned for premium, long tube headers and CAI and it wakes up. 1.6 roller rockers added and an auto tranny LT1 is in the 290's RWHP depending on condition of the engine. A cam doesn't get you all that much because the heads become the problem.

So, compare that to what you have.

 

Wow....lo that actually made sence....i dnt kno much about cars but i kinda got that. then i'll b making real power!!! so the lt1 is an engine...and what is the roller rockers??

 

This is a very good read calderon !!!
Read thru all the 4 pages and you will understand the differences between
Stamped rockers (stock)
Roller Tips
Full rollers
Self align or Non self align , Narrow body and more ...
http://www.vetteweb.com/tech/vemp_07...rms/index.html

 

if i were u i would try buying the "The How to build max-performing small block chevys on a budget" book or similer they will teach you just about everything you need to know and how to make some pretty good power for the street. http://www.amazon.com/Build-Performa.../dp/1884089348 theirs also a couple more listed their to

 

Thanx You Guys I really appreciate all the help....from one camaro owner to the next

 

I agree with getting a book or some other form of research. It is very tough to upgrade something if you dont have a good understanding of how it works in the first place. Your best bet would be to learn everything you can about what you currently have(what it does and why) and then the upgrading will become much clearer to you. Good luck and enjoy.

 

210rwhp!

 

Decent running L98's make between 200-210rwhp on average. I've seen some L98's with cat-backs and at tune make 225rwhp, See 3.8TransAm's posts on his GTA. But that was ALOT of tuning by a guy who is knowledgeable and had the time to spend working on the tune.

2055 headers with a good cat-back should give a solid 20rwhp gain or so which would put you in the 230rwhp ballpark most people have been posting.

I have an iron headed LT1 rated at 260 flywheel HP. Since its a swap I never ran it stock manifolds etc. I have a Moroso Cold Air Intake, Hooker 2055 headers (like you), SLP 2otL cat-back. Its never been on a dyno, however based on the cars race weight at Byron and Cordova (3770lbs with me in it) and its trap speed, the calculators all say its making between 310, and 320 flywheel HP.

So my CAI, Headers, Cat-back gave me a net flywheel HP gain of roughly 50hp. At 3770lbs race weight the car consistently turned 102.8mph trap speeds in the 1/4 mile. Click the video link in my sig if you want to see the runs.

But, each engine was maintained differently, and not all engines are in a factory state of tune so your results will vary.

Dyno'd RWHP can vary day to day, shop to shop..etc. Even your 1/4 mile data can do that too. Dyno's are a tool to see if mods actually gave you gains, the best and most fun way to do it is at the dragstrip.

 

Damb thats crazy. nice car too

 

we just dyno'd my brothers B4C L98 with 160000. it hit 222rwhp all stock except for cat back. the engine was rated for 245 from factory (its a '92). food for thought

 

Its not an unheard of number. 3.8TransAm's 91 GTA L98 scored 225rwhp and 315lb/ft at the wheels with a cat-back too. Its definitely a GOOD number though, a bit higher than average. If I still had a stock L98 i'd be jealous.

 

it does. stock L98. Now it has 1.6 rollers and a ram jet 350 cam. and the heads were rebuilt with valve job. havent had the opportunity to dyno yet though.

 

210 hp 14.7 quarter mile.

 

this would be a waste of money, he has his entire exhaust covered at this power level. money is better spent in other areas.

he would only gain 5-10more hp for an extra 500$. in the future when your trying to make 375 425rwhp would be a great addition.

 

I just wanna mention this that a Cam on an LT1 if you have the supporting mods can be a huge gain. Mainly because the LT1 intake is good to over 400rwhp and its a high RPM intake so it will support a large cam.

CC306 swaps into LT1s with CAI/intake/tune regularly make 350rwhp on stock heads and bottom ends. A CC306 is regarded as one of the largest cams you want to run on a stock bottom end car. It likes gears too, 3.73's to 4.10s as it moves the power up in the RPM range. The highest HP stock headed LT1 I know of is over 380rwhp with a solid roller cam and supporting mods.

The stock LT1 heads flow pretty well, not compared to a AFR or newer LSx head, but compared to TPI heads, its a LARGE gain. These are pretty much the same ports as on Vortec heads. Which is why Vortec heads are such a great budget head.