ULTM8Z

I'm talking 400+ cid...

I'm about ready to up the ante here and go for a 434 cid small block soon. So my question is, since I'm looking for a sleeper, how big a cam would an engine like that take and still sound and idle completely stock; pulling upwards of 17-18" Hg in neutral? I want to use that as a reference point for going just a tad bigger. This is in reference to intake duration @.050 and LSA. I know it's very easy to make 1hp/cubic inch these days, so what I'm looking for is something that you'd never guess makes somewhere in the neighborhood of 480 hp and 500+ ft-lb of torque (until it's too late, of course... )

The rest of the combo would be my Miniram and maybe some AFR 200cc heads.

RBob

iTrader: (1)

Basically, go with the widest LSA you dare. The lower the overlap, the tamer the idle. Marine cams tend to have a wider LSA then car cams.

RBob.

Kevin91Z

iTrader: (1)

Local SoCal guy has one of these XFI280's in his 400ci:
http://www.jegs.com/webapp/wcs/store...0002_363827_-1

Sounds awesome and idles at 800 purring like a kitten. No dyno numbers yet.

Orr89RocZ

iTrader: (20)

go with the best heads you can afford, and then some small cam and great flowing heads will make big power and sound stock or near that.

the right exhaust also will help tame sound, so dont overlook that.

on a 434, you can easily make 480hp on motor. thats why i want a big inch small block, i'm thinking of a 408. For a cam, i'd go with a custom grind, something with near 600 lift and the valvetrain to handle it. like the PAC 1518 beehive springs good to .650 lift. expensive but worth it. you dont have to go big on the cam, i've seen custom grind 383's with duration in the mid 220's at .050 run low 11's at 120-122mph and not a gutted race car either. its all about the lobe design, getting alot of lift and great flowing heads.

with the right sound supressing exhaust, a 230ish duration cam at .050 will be swallowed up on that motor. It will rev to 5500 and probly make an easy 450-480hp on motor with good heads and longtube big primary headers.

For more all out n/a setup i'd look into a cam in the 240's range. that might lope abit tho.

wouldnt overlook a smaller solid roller. I know you can get some solid roller cams with good duration numbers to sound relatively stock at idle.

85MikeTPI

iTrader: (2)

Here's my cam card:

http://www.eecis.udel.edu/~davis/z28.../cam_card1.jpg

The larger cubes cover up the cam really well. This is a solid roller, and pulls 58KPa at 800rpm idle.. (I spec'd it for Road Racing, low-end TQ and plenty of vacuum for the brakes)

Probably even a little too small.. 255/255, .640/.640 112LS

Dyno sessions are at the bottom of the page:
http://www.eecis.udel.edu/~davis/z28/winter01/dyno/

Orr89RocZ

iTrader: (20)

Mike , thats a very nice site there with alot of good comparisons! nice numbers on that motor too!

396V8

hi

i run a comp XFI 467 cam in my 396, 10.8 to 1 comp., and it idles nice and is very streetable...

it would be tamer the more cubes it have to support...

maybe you step up to an XFI 468, or a custom grind....

merry christmas!!

85MikeTPI

iTrader: (2)

Thanks.. It's designed for a purpose, not for 1/4-mile or big dyno numbers.. The single-duration specs were originally for a restrictive exhaust, that may be better-off split now that the Long-tubes are on. The MiniRam isn't the best choice for the low-end specs of the cam either, but 1206 ported EFI intakes are harder to come-by.


Here's a few more combos for comparison:

434 / SuperRam / 236/236 .555/.555 112LS (Hyd) / 45KPA idle



434 / SinglePlaneEFI / 232/236 .622/.626 113.5LS (Hyd) / 40KPA idle



427 / SinglePlaneEFI / 258/264 .648/.667 108LS (Solid) / 72KPA idle

85MikeTPI

iTrader: (2)

I'm guessing this one?

07-467-8 280XFI HR13 230/236 .576/.570 113°LS

Dyno info?

Idle Vacuum info?

What intake are you running?

396V8

hi!

you´re guessing right!!

unfortunately, no Dyno info yet..still in the progress of tuning....

idle vacuum is around 55kpa

Intake is an Accel single plane EFI

Heads are AFR 195cc comp port.

greetings!

ULTM8Z

Are these rear wheel numbers? Or crankshaft?

85MikeTPI

iTrader: (2)

Dynojet chassis dyno.. Rear wheel.

434 backed by a T56 and 3.23 10bolt, the 427 was backed by a TH400 and a 3.73 10bolt.

ULTM8Z

Nice! Music to my ears...

What heads were you running? What's the idle rpm where the manifold pressure was measured?

85MikeTPI

iTrader: (2)

My 427 motor runs hand ported race-ready AFR210s

The 434 runs off-the-shelf race-ready AFR210s

The other 427 runs TFS R-series 215s CNC ported by AES

All of the idle vacuum values I gave are from these specific motors, that idle around 800rpm. The other 427 idles around 1100 though, and the "standard" reference for idle is 1500rpms. (from the carb days I guess)

ULTM8Z

I love the way my exhaust sounds right now- idle sounds almost stock, and very quiet while cruising, but very aggressive on hard acceleration. So, I'm imagining that a 400+ engine will have an even deeper, heavier sound than what I have now (which is fine with me! )

Craig Moates

I've been running the 441 (tall deck Iron Eagle) with 230cc Dart heads / single plane for a while now on a big cam with loads of duration (like 250@.050). LSA is around 110. It makes great power through mid and upper, but when I refresh the motor I'm going to go with a different cam for sure with less duration and a wider separation angle.

It idles nice, but at around 1000-1100. If RPMs dip, it gets pretty choppy. It's a 4/7 swap setup but I don't know how much difference that really made except higher rpm/crank/etc.

I've got another setup (albeit 383) that runs rock solid at 700rpm (224/230, 0.580/0.590, 113).

85MikeTPI

iTrader: (2)

Is that 250 duration a typo? Or did you change your plans to a Hyd Roller, instead of a Solid roller?

Craig Moates

No typo, here's the specs:

0.684"I/0.673"E lift /w/ 1.6RR, stud girdles.
267I/277E @0.050 (300I/319E adv)
110 LSA, solid roller, BBC journal, 4/7 swap.
Lash set at 0.024" hot.

Exhaust is just about wide open (1-7/8-2"stepped huslers, 3.5" collectors to 4" Y out a big aerochamber). Any restriction would just kill the torque curve on this cam.

Intake is single plane with 60# mototron on 730 ECU, SAUJPv3, bigbig throttle body (1350cfm).

Heads are OK, flowed 250/178@0.400", 307/222@0.700". 64cc, flat-top pistons, 0.0075" in the hole.

Valves are 2.08I/1.60E

This is just a datapoint though, I'd say this probably represents the more extreme case of what cam you can put in there and still have it streetable, regardless of displacement. I think it's streetable, my wife and others do not. They're probably more correct.

85MikeTPI

iTrader: (2)

So the "250" was a typo? I'm confused...

My 255/255 duration is a "small" solid roller, your 267/277
is not so "small"...

mike

Craig Moates

Not a typo, just a number I pulled out from a dark place in the absence of valid memory. ;^).

Like you say, the SR specs are going to be very different from HR. These things would destroy hydraulics I'm sure.

Skweezn87

Im the last 427 Mike posted about .. since that dyno graph, I have changed over to a Viper Spec'd T56 from D&D performance. Nice to feel the TQ on the bottom end now.. with the auto the stall would "flash" right on by ...

I have gotten it down to 65-67Kpa @ 850rpms. The idle is a wee bit choppy..but sounds damn nice.

The biggest problem and Mike is too.. is getting the AFR decent while cruising...Just runs PIG rich ..

Like Craig stated.. "streetable" is different in everybodies eyes... I think Craig is on the EXTREME limit of being streetable.. and Im not too far behind!

Mikes car is very nice a "quiet" ... he has the "sleeper" stock look going on..

Ratty Vette

Craig, what are you using for fuel control, ecm wise?

Craig Moates

730 ECU, AUJP v3 modded.

gta324

See sign of video clip from last year, not fine tuned and a bit rich

Cam 227/239 114lobe 9.0:1 around 0.570 lift. Can get exact info if you like (idle rpm/vac and so on)

/N.
----------
forgot the signature...........