I'm kind of debating on whether to run my 292 Chevy naturally aspirated or with a blower.
If I went N/A it would have a Clifford 4bbl intake, lump ports, a Holley 570cfm carb, 1.94int. and 1.60 exh. valves, Ross pistons, long tube headers, and 10:1 compression. Here's the cam specs: 274* advertised duration, .320 cam lift,110* lobe center.
If I went with a blower it would have a Clifford intake, lumps, a Holley 600Cfm carb made for a blower, same valves, Ross pistons, Long tube headers, and stock compression. Should I run the stock cam or some kindof turbo/blower grind(recommendations?)
What do you think about one of the old diesel blowers like off a 6-53 Detroit? that motor is 318 ci, pretty close to a 292. I would go through and put all the needed teflon seals and stuff in it. Do you think it would work? I could play with pulley sizes.
If you go with the blower take a look at the Eaton M90 or if you want a Detroit a 4-53 would probably be a better choice than the 6-53 because of the mounting flanges . The cam will need to be changed to a blower profile cam, but it will all depend if you want to race it or drive it and what it'll be in.
wouldn't the 4-53 be too small? A 4-71 blower is 284 ci, even closer than a 6-53.
Now that I think about it I have a 6-71 blower on the shelf ready for street use, could I just gear that down to about 70% the speed of the engine? Theoretically that would put out around 298 ci.
(6x71=426x.7=298.2)
just saying because I have the 6-71 handy and it's freshly rebuilt.
Sorry what I meant was a 4-71, old age brain casuses fingers to not write what mind is thinking. The 53 series detroits bolt on from under the manifold or with clamps, not suitable for performance use.
I do have A 6-71 blower Handy, and I think I'll try to use that. I'll probally have to mess with pullys to get the right ratio.
Here's how the thread is going elsewhere:
"There is a guy on the H.A.M.B site running an 8-71 on his 270 six, and he says it can keep up with the stupid little ricers on the highway, so I was thinking my 6-71 would probably work fine.
I'm not looking for a full out race motor, but I want to be able to show those ricers what a real hot rod looks and sounds like
If I get 350HP and 350ft.lbs I'd be happy, It'll top at about 10psi boost and 6000 RPM, and It's going to be a daily driver anyway...
Hank, Or somebody, Could you please suggest some cam specs for me?
That'll have me running a Holley 600 (http://holley.com/0-80592S.asp), Clifford intake, lump ports, 1.94I/1.50E valves, Long tube headers, Ross Pistons, and the 6-71 Blower. "
Here's a M90 on a Holden(close to the Chevy 6) from Australia, it can be made to fit up really nicely or at least Barney (the owner) made it look good.
or the you tube ,
http://www.youtube.com/watch?v=uxPUxCcqDg0
Notes:
1) I am not a professional engine builder, or even much of an amateur.
2) I am from the midwest (dirt track country) and I tend to prefer more cam and more rpm than others. Taking that into consideration, I went down a size on everything for you.
3) I have ran a slightly wilder grind in a blown 355 SBC cross-country with no issues. I checked the lash about every oil change and it almost never needed adjustment. In a 292 it will be even tamer. For non-daily drivers, I like roller cams.
Comp Cams: 61-000-0-4875/4877-114+4
I would run a 600-650 double pumper on this setup with manifold referenced power valve. I would also use a mechanical advance only in the dist but that's just me. A high voltage coil and some sort of spark box (msd 6 or equivalent). 1 3/4" x 36" headers if available, or just the biggest diam. long tubes you can find otherwise. 2.5" dual exhaust with ultra-flow mufflers.
I'm a big fan of total seal rings for forced induction applications. Also, this cam/engine combo will require some converter and some gear.
Mufflers? What mufflers? I think it's hilarious when the old granny next to me flips me the bird for sounding like "grave digger"(that's what one little kid said when I had rotted out mufflers and a 216
)
I did a search on comp cams and nothing showed up. you want to post some specs? I was already planning on using MSD, and I already have it. How about a carb like this:
http://holley.com/0-80592S.asp ?
The clifford headers are 1.5 I think, (What I really need is a set like you see in the upper left corner of the screen!)
X2 - needs big primaries.
The M90 is narrowest (smallest left-right) tilted 90°, but it's lower (hood clearance) if upside-down with a U tube over the valve cover into the manifold.
I combined Hank's info with a blower cam Engle had for their small blocks and came out with this:
lift@1.7:i).500"E).510"
Adv.duration:i)272*E)280*
Cam Lift:i)294"E)300"
lobe center:115*
Duration@.050:i)224"E)230"
What do you think? any adjustments?
This is a custom grind roller cam. 248/260 at .050, .672/.686 lift. Ground on a 114 lsa, 4deg advanced. My cam was 255/262 but not quite as much lift, but better flowing head, in a 355 (acts like a 250). I swear this is streetable, blowers eat camshaft. A bit spendy, but this will get you your 400+ hp number no problem with the right stuff around it and that blower.
How does the 4 degrees advance work for you? If I had a cam with my specs do you think I should advance it? if so, how much?
You really need to talk with CompCams about a custom grind.
56er, That's a big ole cam! I want to see how streetable it is. Bet it will sound nasty at idle. Tom
Tom, I promise that the engine I had it in idled at 900rpm all day, didn't overheat in traffic, didn't surge or buck, had plenty of response down low (hey it's a blower motor, there's response everywhere) and did have a lope but not a chop. My friend Jimmy and I had a lot of time in the carb, though, and it had a strong ignition system, and big exhaust.
Qparker, with those specs I would probably go straight up or possibly 2deg advanced. It's really a discussion to have with your cam company. For the record, if you like Engle and have a good working relationship with them, you should stick with them, but the cam in my 292 has similar duration and about .100" more lift. There has been a lot of development in ramp technology that you can benefit from since Engle was doing R&D on cams. My custom ground cam direct from Comp was only 129 shipped and completed in 2 days.
Unless you have a source for the Engle cam in question, you might want to research either Comp or Crower. I was told by a camgrinder over 6 months ago that Engle has shut their doors and is no longer in business. In the economic crunch in the past several years Reed Cams has also closed along with other independant cam companies. So make sure you have an alternate source for the cam of your choice. Website fees are often payed several years in advance, so dont assume that because a site might not have the plug pulled on it yet, that they are still actively in business.
No, I've done business with them in the past and they treated me good. I just talked to Chris about cams about a month ago, he said they were out of 292 cams, but he could have one ground if I needed one...
What do you guys think of me running a water/methanol injection kit?
Snow performance:
http://www.snowperformance.net/products.php?p_cat=324&offset=0
I always recommend methanol injection.
MBHD
Okay, any experience with Snow Performance? are they any good?
I think these cost less.
http://www.alcohol-injection.com/water-injection-kits-1/?osCsid=372d711fde615ef52df9a51de12ae487I think this one of the better ones:
http://www.alkycontrol.com/I am installing one of these on my Syclone.
I think they will all work,just depends on your preference IMO.
MBHD
I have a snow performance stage one. No issues, works well. Currently moving it onto my 292. There are many options for alky kits.
I think I'm going to get Snow's kit, so later I can get the Safe Injection kit for it...
I took this off the BDS site:
http://blowerdriveservice.com/faq.phpIt says :" To measure CFM on a blown engine:
{(CID x RPM) ÷ 3456} x {Boost ÷ 14.7) + 1} = CFM required.
So on a 292 I6 spinning 6000RPM w/ 10#'s it'd be:
(292x 6000)÷ 3456x (10÷ 14.7)+ 1= 851CFM Right?
I also found this to find the final compression ratio:
Final Compression Ratio (FCR) = [ (Boost÷14.7) + 1 ] x CR
That would mean I'm running around 14:1 compression with 8.5:1 base and 10 lbs boost...
Maybe I'd better go with 8:1 to bring it down to around 13:1...
I took this off the BDS site:
and in my previous comment.
Th compression calculation is interesting, but the compression ratio with no boost, 100 lbs of boost, or negative boost is still the same compression ratio.
right, It's the same ratio, different pressures, instead of taking 0 psi and compressing it to ?:1 you're taking 10psi and compressing it to ?:1, therefore starting and ending with higher pressures. It's not 13:1 compression, it's equivalent to 13:1...
Q, that "effective ratio" stuff doesn't really work. There are so many other factors involved. It is true that the more boost and the more compression, the higher octane fuel you should run, but there is no quick and easy thumb rule to quantify it. It really depends on the particular engine's physical characteristics, quench, combustion chamber design, and about a billion other things that people with master's degrees work with for their whole careers.
I wasn't going to go exactly off what the stats say, I was just putting them out there so we'd have something go off of...
it's equivalent to 13:1
No, it's not that either.
c'mon Panic, you're our equivialant to the technical nerd on this board (that's a good thing , not an insult) what is the answer?? I've been trying to find an answer to a similar problem to figure out blower sizes for a particular rpm band and to predict what compression ratio is needed.
I really shouldn't mention this stuff, because on one side there's that great big blower manufacturer, and on the other side there's jus' li'l ol' me... and the laws of physics.
I don't know if they don't understand what's really going on, or (more likely) they realize that most people visiting are looky-loos (not buyers or owners), and a complex answer will just tune them out.
The answer given, "final compression ratio", stating flatly that's it's a ratio, is a poor choice of phrase. Why don't they say, as qparker said "the equivalent"? because that just precipitates another question. They're not in the question business, it doesn't pay well.
The pressure does go up, but nothing like as fast or high as shown. However: the results (although the math is bad) are useful in that they're all conservative. A really complex answer will not only give the new pressure equivalent, but begin with the original pressure.
???
Yes, the original pressure was perhaps 1 psi of vacuum (2" Hg) for a hot V8, so the increase is larger than it appears (10 psi is not 10 higher, but 11 higher). However, for an under-carbureted motor such as a 250 with perhaps 2-4 psi @ WOT 10 psi is much higher (12-14 higher), and would give results closer to their math.
Clint Gray did the research for this, I just worked out the language:
http://victorylibrary.com/mopar/blower-engine5.htm#ECRBTW: they finally put that CFM calculator up... after mine (and perhaps others as well) was pointed out to them.
Are Roller Rockers Really worth it for my application? They're $450+/- at comp cams and for $50 I can get "high energy" rockers for $50 at the same place...