want your input on next engine guys

[grumpyvette]

now I know you did not really ask, but you might want to look at this, its a rough idea still needing careful parts matching checks, before finalizing , its for a serious race only application, and at this point the combo needs tweaking, if anyone can post a picture of the DD DYNO power curve Id appreciate it as I can,t POST that PICTURE

 

Corvette Dream engine, the ideas to get 700hp before the giggle gas injection,AND not to exceed 6000rpm, maximizing power from 3000rpm-6000rpm is the concern, I don,t want to change the bore/stroke or cylinder heads feel free to point out potential problems its still a rought draft idea at this point , its similar to other engines Ive built but with several new part designs and yeah its only going to see 115 octane not pump gas

 

TALL DECK 4.5 bore Block #083111

http://www.worldcastings.com/docs/05_cat_pg7.pdf

heads #020750-4 …….345cc

http://www.worldcastings.com/docs/05_cat_pg23.pdf

intake single plane dominator style

http://www.worldcastings.com/docs/05_cat_pg27.pdf

crank 4.375 stroke

http://www.dougherbert.com/chevy-4340-forged-profiled-cranks-p-12960.html?cPath=1_359

solid roller cam

 

http://www.dougherbert.com/8620-billet-roller-lifter-p-9820.html?cPath=83_84_87

roller lifters

http://www.dougherbert.com/catalog/product_info.php?cPath=83_93&products_id=10117

 

rockers

http://www.dougherbert.com/catalog/product_info.php?cPath=83_284&products_id=12702

 

pistons

http://www.kb-silvolite.com/forged.php?action=details&P_id=399

 

RODS/ 6.8†eagle

 

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=1240&prmenbr=361

 

dominator carb, 1150cfm

 

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=401189&prmenbr=361

 

500hp nitrous direct port injection

 

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=3771&prmenbr=361

 

oil pan

 

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=1756&prmenbr=361

 

 

yeah, its a 14:1 cpr 555 bbc, yeah the pistons are .058 out above deck ,unless machined, if the decks at minimum, they will be custom fitted or replaced with custom made

[strotter]

Grumpy!!! A CA ... A CA ... A CARB? Man, you're the one that inspired me to get into mpfi! Your word at thirdgen diy-prom is scripture! Heck, it is here, too!

 

Room spinning - world turned upside down - must - hold - on...

[grumpyvette]

DON,T PANIC Ive got the COMPLETE MPFI setup ready to install, the carbs only listed to make it easy to dyno

[pparaska]

I only wish I could give YOU advice on matching components!

 

I'd be happy to run a DD2000 run for you. But I can't find flow #s for those heads ANYWHERE. Any ideas?

[grumpyvette]

 

you can use these specs from the AFR 345cc head the differance is minor and the new heads are supposed to slighly exceed those specs

[pparaska]

I had trouble uploading pics tonight too. Not sure what's up.

 

Anyway, I used your data, the AFR flow numbers, the Chet Herbert cam specs (seat timing, lift, LSA), 1150cfm @1.5Hg carb, "Large stepped tube race headers", "single plane" manifold. One run without Juice, one with 20lbm/min of N20 (since they only went up to 400 hp shot in the pull down which gives 16lb/min). Here they are:

 

No N20:

http://alteredz.com/data/grumpyvette555BBC_nojuice.png

 

20lbm/min (500hp shot) N20:

http://alteredz.com/data/grumpyvette555BBC_20PPMNOS.png

 

Tabular form:

 rpm     hp   ft-lbs
2000   228   599
2500   320   672
3000   405   709
3500   489   733
4000   577   757
4500   664   775
5000   734   770[b]
5500   780   745
6000   781   683[/b]
6500   764   617
7000   720   540
7500   666   466
8000   601   394

 

HP Peak is somewhere between 5500 and 6000 rpm. Just what you wanted!

 

N20:

 rpm     hp   ft-lbs
2000   743   1951
2500   827   1738
3000   907   1587
3500   990   1486
4000   1078   1415
4500   1161   1354
5000   1227   1289
5500   1273   1216
[b]6000   1279   1119[/b]
6500   1266   1023
7000   1227   920
7500   1177   824
8000   1111   729    

 

HP peak looks to be right around 6000 rpm!

 

What a beast!

[Tim240z]

Here ya go Pete/Grumpy. (Pete, it has to be .jpg. .Png won't upload)

 

 

[Michael]

Questions for you, Grumpy –

 

1. To what extent should we trust those DD2000 numbers? 1951 ft-lbs at 2000 rpm??? Running a “junior version†of your engine (461, Brodix Race-Rite oval-port heads, 0.640†mechanical roller, dual-plane, 750 cfm, also 6000-rpm limit, but no nitrous) on DD2000 ad nauseam I also get remarkably good numbers – like 596 ft-lb at 4000 rpm, 559 hp at 5000 rpm. In my application, by the way, DD2000 predicts a drop of almost 150 ft-lb in going from 5000 to 5500 rpm.

 

2. Are those lifters similar to the Isky Red-zones?

 

3. I understand the quoted bore limitations with that block, but why not a larger stroke?

 

4. Any nitrous-specific considerations for the cam, such as greater intake duration than one might have chosen otherwise?

 

5. Would the deck have to be O-ringed?

 

6. What sort of valve spring pressures would be needed? Would you need a shaft rocker system?

 

7. At this power level, are there any symmetric-port heads available with “smallâ€-enough (as opposed to pro-stock) intake ports?

[Michael]

Oops, disregard question #2 - they ARE the same lifters.

[grumpyvette]

Questions for you' date=' Grumpy –

 

1. To what extent should we trust those DD2000 numbers?

 

[b']the peak numbers ant the rpm peaks suggested are normally close to correct PROVIDED ALL the DATA is correct but the tq figures below about 4000rpm are usually predicted well higher than the true dyno results[/b]

 

 

1951 ft-lbs at 2000 rpm??? most likely BS, but keep in mind you don,t inject nitrous below about 3000rpm and usually have a swithch that tuns it off at 6200rpm if the rev limiters set to 6100rpm

 

Running a “junior version†of your engine (461, Brodix Race-Rite oval-port heads, 0.640†mechanical roller, dual-plane, 750 cfm, also 6000-rpm limit, but no nitrous) on DD2000 ad nauseam I also get remarkably good numbers – like 596 ft-lb at 4000 rpm, 559 hp at 5000 rpm.

 

again most likely optomistic

 

In my application, by the way, DD2000 predicts a drop of almost 150 ft-lb in going from 5000 to 5500 rpm.

id suspect thats B.S. also, keep in mind that DD-2000 its a useful tool but not a serious representation of the whole power curve, Id suspect that only the PEAK numbers are close

 

 

 

 

3. I understand the quoted bore limitations with that block, but why not a larger stroke?

its got to do with piston speed and stress on the engine parts, a 4.375 stroke , hits 4000 fpm in piston speed at about 5500rpm, 4500fpm is at about 6200rpm, you generally run into long term problems with stress, bearing wear,ETC once you exceed 4000fpm , but once you exceed 4500fpm your looking at a serious reduction in expected engine life, thats why G.M. gave thier 572 a 4.37" stroke vs the more comon 4.5" used in building a 572 displacement , look

http://www.sallee-chevrolet.com/ChevyBigBlockV8s/572.html

 

4. Any nitrous-specific considerations for the cam, such as greater intake duration than one might have chosen otherwise?

 

the cam selected is a compromise designed MOSTLY for NON-nitrous results, IF Id sellected a NITROUS cam it would have a large LSA and more exhaust durration plus an earlier exhaust valve opening point, keep in mind IM not building this as a all out race engine, its a high performance engine that might see some extremely limited street use.

 

5. Would the deck have to be O-ringed?

 

NO, but then Id use soft copper head gaskets without the (O) ring which has proven to work just fine in other nitrous BBCs Ive built

 

6. What sort of valve spring pressures would be needed? Would you need a shaft rocker system?

I detest shaft rockers due onlyto the increased costs and avoid them if the application does NOT REQUIRE thier use,,

 

Id use THE MINIMUM spring pressure with the max clearance I think I could expect to run correctly, in this case Id sellect something in the 225 ftlbs closed to 600ftlbs open range

 

7. At this power level, are there any symmetric-port heads available with “smallâ€-enough (as opposed to pro-stock) intake ports?

 

yes, but the costs go up a great deal,I don,t think the results are worth the cost differance if your not racing as a bussiness vs a serious hobby

[Michael]

Understood about the piston-speed constraint. But what do you think of the following train of thought: going from a 4.375 to a 4.5 stroke (for example) is only about a 2.9% increase in piston speed and displacement. If the engine maintains the same peak volumetric efficiency, peak torque should rise by the same 2.9%. And if the rpm for peak V.E. goes down by 2.9%, peak hp stays constant. However, for the same compression ratio the 0.125†extra stroke buys a 2.5cc reduction in piston dome (if I recall correctly the specs of your heads) to get the same compression as with the smaller stroke– and conceivably, with the smaller dome the result is a slightly lighter piston with slightly better flame-front propagation, hence better combustion efficiency. So, because peak hp hasn’t budged, the benefits in a racing engine are questionable – but in a street engine, especially in a relatively heavy car like the Corvette, the trade of extra stroke at the expense of reduction in peak rpm might make sense. Do you have a broad choice of gears for that Dana 44 (or whatever differential the Corvette uses)?

 

BTW I’ve heard elsewhere that copper head gaskets are tough to seal for an aluminum head/cast-iron block application (yes, I know that your application is an aluminum block). This seems counterintuitive, and contradicts some discussions on this site – including, if I recall correctly, your posts. What’s your opinion on copper head gaskets in the 0.040â€-thickness range?

[grumpyvette]

Understood about the piston-speed constraint. ...............the trade of extra stroke at the expense of reduction in peak rpm might make sense.

 

since the engine uses FLAT TOP pistons and 80cc cmbustion chamber heads with 14:1 cpr theres no gains to be had removing a non-existant piston dome' date='your correct about the increased stroke and resulting displacement increase ,in that it would more than likely aid rather than hinder the power production, even at the expence of a small loss in mechanical efficiency. GOOD POINT, thats why I posted,this Ill consider it and do the math research necessary in detail.........btw theres other factors like bearing oil film surface speeds and internal load/drag, that also tend to cause potential problems once that 4500fpm is reached,the stress is not linier its on a geometric progression as the stroke increases . a 3% stroke increase could easily result in a 8%-12% stress increase[/b']

 

Do you have a broad choice of gears for that Dana 44 (or whatever differential the Corvette uses)?

 

youve GOT TO BE kidding about useing a corvettes dana 44,INDEPENDENT REAR SUSPENSION on an engine like this will twist that flimsy junk up on the first launch, Im probably installing a solid axle 4 link dana 60, but once I do the math I may be forced to install a 11.5' truck DANA rear like the pro mods use

 

 

 

 

 

 

BTW I’ve heard elsewhere that copper head gaskets are tough to seal for an aluminum head/cast-iron block application (yes, I know that your application is an aluminum block). This seems counterintuitive, and contradicts some discussions on this site – including, if I recall correctly, your posts. What’s your opinion on copper head gaskets in the 0.040â€-thickness range?

 

Ive never yet had the smallest problem useing solid copper head gaskets, I am useing them currently on several iron engines with aluminum heads including my corvette 383 which sees a 200hp nitrous boost ocationally, I guess I find out thru trial/error if an all aluminum combo reacts similarly