Should I stroke my 350 or use a SHP 400 block? The 400 option should cost an extra $1200. Is it worth the investment for the added power and/or streetablilty?

My target is an honest, streetable 360 WHP. The plan is to keep the HSR intake add CI, AFR heads and a healthy cam. The top end cost is about the same either way. The difference is the short block.

Stroking my 350 will cost ~$2k with forged pistons. A Dart SHP block adds about $1,000 plus a few additional costs such as oil pan/timing cover etc.

From research I've done it looks like the 383 would need ~230 duration cam for this power level and the 400 should be able to get away with less and be a little more street friendly. Conversely, could I get away with the same or more cam in the 400 and still have a decent idle vacuum?

Bear in mind I'm running power brakes and a TKO 5 speed. I tune my own program on a MAF system. Any input on the two combinations to meet my goals will be greatly appreciated.

I don't intend to debate whether a 383 or 400 is better, rather which one is the better value for the same HP, Tq and drivabilty goals. Bottom line is the SHP + CI gain worth $1200?

Ant

 

For only mid high 300's whp, keep a L98 based block stroke to 383, run Afr 195 heads with a 280xfi and it will be 375-400whp easily and drive fine

Could even step cam down alittle with custom xfi series or other lobe, 226/232 xfi on a 112 will be awesome

 

Thanks Orr. What about the 400 based combo? Do you think I could get to hi 300's and keep it streetable? What cam specs would you use keeping drivability and torque in mind?

 

Yeah a 400 will make big power with same cam and be alittle more streetable than the 383. Xfi is abit aggressive but they work. Could do a similar lunati voodoo. Afr 8019 springs for certain. Dont need a 230 deg lobe to make 360's on a 383 but comp doesnt offer anything inbetween 268 and 280 without goin custom.

400 Shp is lot of money for 360's hp. It makes more sense for 400-500whp

 

Well I did say an HONEST 360. That is my minimum target with a >10lb/HP goal. I don't want to underestimate driveline loss. More is certainly better but I want to keep it MAF friendly. Mid torque and drivability are desirable to maintain. I went conservative on my 350 build and want to bump it up a few notches.

For the 383 is ~230/112 cam still streetable?

And XFI cams too aggressive? Are you referring to the lift to duration ratio here? They do seem to offer more lift-to-duration compared to other grinds. Does this cause valve train wear issues?

 

The xfi are aggressive. Look at the advertised duration, .050 numbers, and .200" lifts. Lot more duration at .200" compared to other cams is aggressiveness. Require good stiff springs to control over 5800 rpm. Afr's 8019 option will work. They will go several 1000 miles before requiring a new set of springs, so no worries there but they are no stock cam 100k mile stuff if you know what i mean. You can do a milder xe lobe or something if you want comp cams. Plenty of options out there. Custom is also on the table.

But with afr 195's, hsr and a decent lobe cam will be hard not to make over 360 whp. Most likely 380-400. I have tuned a 280xfi in a 360" motor and it was alittle aggressive in those cubes but mass air was fine and it ran on stock converter so its def streetable. Just had a rough idle. Everything worked tho

My 383 hsr with a big nasty cam ran very hard but despite its aggressive idle it was a very driveable streetable car. I can send you the specs and you can order it from comp cams. It was on a 109 lsa pulled to 7k and made 400whp, ran mid 11's. probably abit more than you wanted tho. Thats why something in the mid 220's duration xfi lineup on a 110-112 lsa would be killer

 

My previous engine was a 383.
I had afr 195's, with a 280xfi flat tappet cam.
1 5/8 shorty headers and open exhaust thru a 48mm throttle body.

The 383 had flat top pistons with 11-1 compression.
I made 377rwhp. I did a 12.09 @ 111mph with open exhaust n/a.

With long tube headers and a 58mm throttle body I would have been in the 11's no problem.

 

Orr, Lb9- maybe I should clarify my goals here. When I say an honest 360Whp I mean average over the rpm band. From shift point drop to the next gear. It is a little more from 1 to 2 but you can say 1500RPM. So lets say the shift is 6000, I want to average 360WHP from 4500 to 6000. I have been using a 20% driveline loss so at least 450Hp from 4 to 6K. Peak is great but the average is more important to me.

 

Well if that is your goal either engine would work with the right parts another option would be a destroked 400 to make a 377 ? I believe which would be a screamer high RpM motor ... But I think the 400ci engine would give u a better average ... While the smaller engines would be a little more "peaky" with the same parts applied
... But with your goals in mind I think u need to be atleast 10.5:1 SCR, aluminum heads, 230+ duration @ .050 , good intake , and good valve train should get u there .. Are u planning on a forged bottom end ? All arp bolts and studs ? Balanced bottom ?also some good 1.75" long tube headers would prolly b best ... Come up with a combination and cam specs u are thinking about using or even 2-3 diff combos and I'll plug the numbers in desktop dyno in give u some numbers ... I'll also need head flow numbers to have a good estate

Another option would be a smaller cheaper engine with a procharger to make up the cost difference but may not last as long if ur gonna have ur foot in it 24/7

 

Well setup 383 will do that. You'll need closer to 400 lbft at tires in the 4000-4500 range and shoot closer to 400 whp at peak to come out with a bettter average over 360. A 400" motor with a 195-210 head will do abit better job. 195 head for up to 6000 rpm, 210 for up to 6400 or so. Something around 230 deg at .050 and you easily have this goal.

Dont be afraid to spin it up tho, hsr with a good heads cam starts making best power over 6000 rpm. And still be very driveable. Can make decent trq but you will have a power curve more like lsx stuff. No huge tpi trq spikes. Common to see 375-390's wtq. A 400" shp will do 20-40 lbft more.

 

Ok everyone thanks for the input. I very much appreciate not only helping me consider the value either way but also the build specs to get there. It really does help hearing from you with first hand experiance.

From what I am hearing either build should achieve the goal. With a slight power advantage to the 400 but it would probably be a more streetable version- power & torque better in the cruise area.

The build will be very simular either way. Cast steel crank, stroker rods, forged pistons. Favoring the AFR heads but Dart Pro 1's are an option too. 10.5-11SCR ~330/336 cam at 110-113lsa 520+ lift. Roller lifters/rockers. HSR intake and (for now) 1 5/8 shorty headers.

383 specific
2 bolt block (did I mention that I have a nitrous kit?)
May use AFR 180's here? or 195

400 specific
Dart SHP 400 block same internal specs.
Probably use AFR 195's or Dart Pro1 200's

Trying to reach HP target but keep it daily driver friendly. 3.27 rear with TKO OD nets a 1800 @ 55 & 2200 @ 70 cruise. Would llike to keep a 6000RPM max just so it doesn't get too exotic. 7-800 rpm idle would be nice too as long as it keeps the brakes functional.

AFR flow specs per their website if anyone wants to crunch the numbers for me...

@ cc 180's 195's
.2 138/110 146/119
.3 198/158 201/166
.4 240/190 274/197
.5 260/207 275/213
.55 ------- 280/218

AFR has a dyno'd engine 383- 230/236 cam engine with their 180 heads that makes the numbers & one with 195 heads, slightly more cam that should be good for sure. It even makes more torque @ 2500. (I usually use 20% loss but engine dyno numbers seem to be inflated at least from the headers used and lack of accessories so maybe I should figure more loss)

The bottom line is if the 383 will make the goals it is less $$ for me. I go through the engine I have and save a bunch on misc items (pan tc bolts spider etc) plus the cost of the block.

On the other hand the 400 will be a ground up build with the differance being cost of the block & misc. If money were no object this would be the way to go. (well maybe id go 427+) But I don't want to get cought up on ~$1200 bucks on a $5k+ build. This option would also leave me with a complete, running 350 engine. Flat top, Comp cam procomp heads pan to vc. Maybe I could recoup some of the cost here. Experiance tells me that $5-750 would probably be about all I could get though.

 

Hard to sell sbc's anymore.... Budget lsx takeouts rule the streets these days. I lost alot on my 383 on resale

I would go 195's for either build. No bigger than a 230-ish deg at .050 for best shot at cruising low rpm in the manual trans. It will run very well.

 

I think my current engine is close to an engine you ran once; 383 with ported AFR 195s comp cams 280XFI, 10.5:1, 1 3/4 header, single plane efi intake. I have a manual transmission in mine and with a 3.42 gear it has no trouble in regular traffic, only place where it doesn't want to be tame is creeping in parking lots or in traffic that is moving really slow, like walking speed slow. I think with a gearing of at least 3.73 I wouldn't have that though. I haven't had the opportunity to dyno it or really go north of 3K rpm as I just put 500 miles on it before I put it away for winter. Definitely stronger than the last 350 hot cam trick flow engine I had, stock compression ratio and conservative fuel and spark maps and I still had 330 hp on a mustang dyno.

I would recommend you also go with a 383 or just start building an LS setup. Skip the 400. Your trans may or may not bolt up to an older 400 and if you want to use a roller cam you will be spending more money for a retrofit kit. The LS stuff used is getting cheaper every day and its easier to go fast with it. If you are building a new engine and you are able to throw around words like forged and new AFRs, you should look into the cost of converting to an LS setup because just like Orr said, you will take a huge hit if/when you sell that engine.

 

Excellent points guys. Especially when comparing the Dart/400 cost to the LS option. And the only "value" of a used engine is if you need one for another project. Thanks for the input. It looks like stroking my engine is the best value. I just hope it gets close to my goals without being an animal.

And when it comes to the LS subject... Sometimes I feel like it's 1969 and I'm trying to build a really nasty flat head. Dollar for dollar, power to power it just doesn't make sense. Once the cost of building a classic gen 1 motor goes past around $8k the LS change over is starting to get within reach.

I wish I could "throw around" words like AFR lol. It's a big justification for me and 30-40% of the build costs. I feel like it's my only option to get close. Otherwise I'd just freshen up my ProComps. Overall they seem pretty good and would save another $1000!

Hmmm, I wonder if the old TPI manifold is going to be "remembered" like an Offy manifold an 3 stromburgs?

 

Antman - I dynoed my 383 many years back with AFR 195's, MiniRam, Comp XE 230/236. We ran 20 dyno runs and the result was 385rwhp @ 6500. The MiniRam really likes the rpm. The highest hp pull was with coolant temps at 220.

 

AFR is not that much more than anything else out there thats similarly prepped in valvetrain components. Heads are the one place you should not skimp out on, and if it costs the most out of all the other parts of the build, so be it. My heads and valvetrain cost as much as my aftermarket block forged shortblock.

 

Were the other runs at cooler temps? My car seems to like 200+f.

I presume that cam was at 110 LSA?

Also, how did your combo run at idle & cruise speeds- say under 2500? Do you know how much vacuum you pulled at idle?

Orr, I completely agree with your statement regarding head choice. Like I said it's a big percentage of the build cost and if you consider the entire valve train it is easily 50%. There is no other bolt on approach I know of that will give the desired results so I'm including it in my budget.

I do however, wish I had time and budget to try a few different cams. That's why I am asking so many people for input. I really do want to keep the lower rpm torque and manors street friendly. So far I like the 280XFI the best but am still considering a milder cam such as the Xe276. 224/230 on 110 or 112.

 

Good thing is with good heads, you can cam small and make good power with good driving manners.

I really think an xfi cam that falls between the 268 and 280 is what you want. 280 isnt big imo but i have higher tolerance for things like this and an automatic.

Custom grind may be your best bet. Sounds like you want peak power closer to 5800 shift by 6200. Which will be something around 224-226 deg with good lift. 111-113 lsa is fine

 

Interesting, would you mind posting some other info about the engine? compression ratio, headers, fuel injectors, ECM system, Final spark under WOT, etc,.

 

The motor had 10.5-1 comp, the cam has a 112 lsa 4 degree advance. Hooker Super Comps flowing into dual 3 inch converters then into a 4" mufflex system. I ran a 160 stat but this was summertime and with all of the dyno runs, temps were climbing high.

With this tune, the car went 11.80 @ 115. I later installed a solid roller 236/242 on a 112 lsa and advanced timing to 38 deg total. Car went 11.60@118. This again was through the full exhaust including cats.

I eventually broke a rod at 6k and it put a fist size whole in the block. I then built my 406.

I never did dyno or 1/4 mile the car with the 406 but it's a completely different car with the 406. The car is absolutely violent from a 20 roll.

The 406 has stock crank but 6" Eagle rods, JE flat tops and is zero decked. Im running Brodix RR200 heads with 2.05,/1.60 valves. The cam is a custom grind 238/246 .625 lift on a 110 lsa installed at 107. The twist on the cam is that it's a 4/7 swap. The motor pulls hard to 7200 and idles very well. In fact I passed an Ohio e check. Throttle response on this combo is the best of any motor I've built. I did screw up by using the stock crank. It wasn't up to the task of running high rpm and last fall I bent the crank. Im now in the process of pulling the motor.

Sorry to have been long winded but if I were making the decision between the 383 and 406, it would be the 406. I strongly urge you to zero deck either motor. Keep the quench at .040 and the motor will be much less sensitive to detonation.

 

Please, "wind"-on... Want all input possible!

In regard to the 406 and the 4/7 cam. 1) was it solid or hyd, flat or roller? 2) what is the advantage of the 4/7 swap? I understand what it IS just not exactly why. Seems it still leaves same bank cylinders firing at 90' but maybe there are other reasons.

And I possibly didn't pay attention here but was this with HSR or what induction system? What are you controlling it with OEM computer?

 

The cam's a solid roller with an aggressive ramp. There are theories out there about firing order swap. Its supposed to make the engine smoother and pick up hp at the top end. To be honest, I did it to be a little different.

I ran both Miniram and single plane intakes. The single plane offers better idle quality. Overall performance, I preffered the Miniram.

 

Love it! That is one of the reasons I am drawn to a 350 based 396. Cause it's not the same ol 383. (not to knock em)

Hmmm. I wonder why this is? Assuming single plane is EFI and has about the same runners as MR would it be the plenum size difference? Seems it would be the other way around regarding idle quality.

Not to hi-jack my own thread but I have thought about using a dual plane type manifold with port injected EFI. Just to pick up some of the idle/low rpm qualities of splitting up the cylinders due to cam overlap.

 

Miniram feeds from front of plenum and thus front cylinder pairings may see different air fuel ratio than rear. Its quite common. Hsr same way but i think to a lesser extent because the plenum i beleive is larger

Single plane feeds from common center and usually much better distribution