ZZ4 86 Z28

iTrader: (1)

Hey guys, before I go any farther i will talk about my combo. I have a zz1 crate motor...that has aluminum corvette (l98) heads, a 235/235 hydraulic roller cam, an accel 58mm throttle body, K&N filters, edelbrock headers, flowmaster catback, an auto and 3.73's. But theres a small problem...the previous owner just took the stock tpi off the 305 and threw it on the new motor! thats right, stock manifold, plenum, runners, injectors, all that crap. anyhow, i was thinking of going with an hsr, but a few people told me just buy some slp runners and port the crap out of the plenum and baseplate, and cut the divider out of half of the runners. how would you compare the gains I could see with each different setup? Also, what do you think I am at right now for fwhp,fwtq,rwhp,rwtq, and what do you think the numbers would look like after changing to the different setups? thanks a lot, and also, if you have any other ideas for intake setups that would work good and not cost a fortune, let me know.

And also, do you think its time for new injectors? the stock ones are only like 19lb right? thanks a lot.

327_TPI_77_Maro

iTrader: (8)

HSR will make tons more power than a "home ported" stock base with aftermarket runners slapped on. The gains above 5000 rpms will be very very noticeable.

DZcode

ZZ4,
Take a look at the graphs on the shootout sticky above.

https://www.thirdgen.org/techbb2/sho...hreadid=273727

I'm was trying to figure out what induction setup to use on my 406. I used that article to decide on an Accel/Lingenfelter and SLP runner set up - or basically a larger manifold and runner. I picked this combo because I want the engine to be streetable and I'll probably never spin the engine past 5200rpm The tq and hp between 0-5000rpm was better for me with manifold and runner. (Engine not running yet, just sitting in engine bay.)

It is difficult to give up the hp above 5500 that the HSR provides (not to mention that manifold is cheaper too), but most of my engine time will be below 5000 and I didn't want too give up the hp/tq the HSR lost down there.

Deciding where your engine will spend most of its time will help you select the right intake combination.

VR,
DZcode

ZZ4 86 Z28

iTrader: (1)

i think im liking the look of the ported tpi better. like you say more streetable. ill never be hitting more than 5500 rpms. my new motor has a suggested top rpm of 5800 anyways, and i do not wanna push it. plus for just the price of runners, and some free work (im painting a dudes car and hes gonna port the plenum and base for me) it will be cheaper too. thanks a lot.

Also, anyone have any ideas of the numbers i have now and could expect? if the amount of torque lost isnt too much, but the horsepower gain is insane, i might change my mind.

327_TPI_77_Maro

iTrader: (8)

You will literally be giving up 40-50 hp with a stock base, arftermarket runners vs the HSR. Look at the shootout the other member posted.

1BADROC

iTrader: (1)

id go with hsr its very efficient, the torque loss doesnt exist if anything i gained torque. all i did was put some headers and hsr on my stock motor and gained around 80 to 90hp and 9 tenths at the track

TPI Monte SS

If you're gonna leave the cam alone, you could really get away with stock-ish TPI parts. The ZZ4 cam is rated to make peak hp at 5200 rpm, and a modded TPI can pull that easily. Why worry about making power above 5K if the cam is done by that point?

Now, if you're gonna step up the cam and do something wilder, then by all means go for the HSR. Cost is about the same, depending on if you find good used deals on certain stuff.

Buddy

That's actually not really the way to go. I had that same cam - 235/235 (480/480, 114) for around 8 years. It came out this past summer. If your going to keep the cam, go with the Holley Stealth, if your willing to change the cam, stay LTR. You have to have all of your parts match. Decide if you want a racer, that makes great HP at buzzed up to 6000, or a streetable car with great torque that never see's above 5500.
Make your decicion based on the purpose.

ZZ4 86 Z28

iTrader: (1)

streetable car that never sees more than 5500. i dont plan on changing the cam or heads, i just know i got to do something about this intake. and the cost of the hsr would be much more. i just want slp runners. cut the divider out, port the base, and port the plenum. that would all be for the cost of runners. the hsr would be the hsr manifold/feul rails, new remote coild distributor, cutting the stock hood, probably more tuning (i wnted to ask more about this too), and the feul line adapters. so a FULLY PORTED tpi compared to hsr would be about 40hp less, and minimal torque loss? that makes it seem kinda worth it. anything else i would need for the swap?

Still waiting on if anyone would guess some output numbers. i forgot to mention 9.8:1 compression. thanks a lot.

Shagwell

...I'd bet on closer to a 50-60hp loss. No major difference in peak torque number, but it'll be at a different(higher) rpm level(w/ the HSR). - I've been knocked for my always recommending this, but have you looked into the FIRST intake? - would be perfect for what you're looking for. do a search under BadSS/FIRST intake. he's ran a modded TPI vs HSR vs FIRST on his motor. His posts have all the info you're looking for.

ZZ4 86 Z28

iTrader: (1)

yea i did look at a first, but i have centerbolt heads, and they cost a pretty penny. and i would still need the dist swap on top of it.

Orr89RocZ

iTrader: (20)

HSR should make a flatter torque curve than TPI's more peaky curve.

with that cam and HSR, it will be a good match. those heads tho if not ported will hold back BOTH the cam and heads.

TPI would be a good match for the heads cuz its flow isnt as high as the HSR...but as is, either HSR or TPI will out flow the heads anyway.

ZZ4 86 Z28

iTrader: (1)

yea, i was gonna get those ported to a 1205 also. if i dont get the tpi ported, he will port the heads...maybe both. thanks a lot for the help. it really seems like you guys are urging me to go with the hsr setup. seems like a better idea now, especially since it will match up with my cam. thanks a lot guys. how much hp and torque should i expect at the crank and at the wheels?

327_TPI_77_Maro

iTrader: (8)

Gasket matching the centerbolt heads to a 1205 alone isn't going to help you at all. The ports are so narrow compared to a 1205, and the casting next to the pushrod area is so thin, you could never open the ports up to a 1205 width all the way through. The best you can do is flare the mouth of the port so the air isn't hitting the edge of a sharp, smaller sized port. The HSR is not 1205 sized ports out of the box, for sure, they are quite a bit smaller. I checked my HSR against some 1205 templates when I had it off a little while ago. There is a lot of material that can be taken out of the pockets and throat to open those heads up. Guys take up to 10ccs out of the pockets on the iron heads, I'm sure the Al heads port in a very similar manner. I spent probably 25 hours porting my iron centerbolt heads, and there was still a lot more that could have been done.

ZZ4 86 Z28

iTrader: (1)

oh, then ill gasket match the heads to the hsr. will i have to do the same thing about not going in too deep?

DZcode

http://www.eecis.udel.edu/~davis/z28...age021105.html

Tq increase in the lower rpms with ported TPI compaired to gained horses above 4600-5400 rpm with the HSR.

You're not giving up 50/60 hp until you're spinning 6400rpm.

Orr89RocZ

iTrader: (20)

thats a siamesed tpi setup... it will make more power than regular TPI and act more like a HSR or similar cuz siamesing makes the effective runner length smaller.

and that cam is more suited to HSR than TPI.


but in general, compared to LTR tpi without siamesing.. HSR makes abit more power, especially around TPI peak rpms. its worth it in the end cuz its cheaper (new hsr vs new TPIbase/runners)

ZZ4 86 Z28

iTrader: (1)

i got more than just the hsr to buy...including a new distributor. i was only gonna buy runners, and port the base and plenum. so it would be way cheaper for me to just go with the slp runners, cut those up, port everything else. ill have to check out where the power is better for which intake. it seems like money might only allow me to get the slp runners and get started on some porting.

ok, i looked at the chart. the numbers arent even poisitve until around 4600 rpm anyways, and dont hit an increase of 30 until after ive shifted. i dont think its worth the extra money for me, especially considering the losses where i would be using the power most often. thanks a lot for the help guys.

Orr89RocZ

iTrader: (20)

i think you would really benefit from a aftermarket base as well... fully ported stockers dont hold a candle to mild ported/cleaned up aftermarket units like big mouth and superam base