Just finished building an engine for a friends z28, and wanted some ideas what the hp and torq #'s should be. I have a decent idea but let me know what you think...

305 bored .030
11.0 to 1 compression
416 heads
single plane weiand intake
650 dp
228/.468 cam
roller rockers 1.5
1 5/8 headers

I was thinking close to 325, what do you think?

 

Sounds good . But with the 11:1 C/R and the 416 IRON heads . There may be some detonation issues . Might need some special gas ???

 

what are you thinking with a single plane intake? The heads and cam are going to be out of steam by the time the intake comes in.

 

I would say that you are looking at an engine that wont make much down low, wont be able to make much up high, and will take race fuel to run.

 

Same thoughts here.

Looks like you didnt do much if any planning while this was being built!

 

I seriously doubt you are at 11:1 compression. Maybe more like 10:1.

I got away with 10.3-10.5:1 with 305 heads on a both a 350 and 305, with 93 octane gas. I have always run a knock sensor though which is extra insurance.

 

Really? I figured he was runnnig a 305 so he could get a bit up top .


How did you get 11:1 if you don'mind me asking ?

 

What's your reasoning behind that? A motor will only spin as high as the heads and cam will let it.

 

...Or the intake . My reasoning is ..... The 305 has less cubes ...less demand for air ...so it will pull more revs with an intake that chokes a 350 around 4600 ....might let a 305 rev to 5000 rpm . I am not saying I am correct ....it's just a thought .

 

well first of all it will be fed only a steady diet of 110 octane, so no detonation issues. Secondly the intake is rated for off idle to 6500 rpms, the cam is rated for 2500-6000 rpm, and that number will move when used on a smaller displacement engine, if anyone wants to take a look at hitech.com on there 343 hp 305 I have basically built the same engine only more compression, more cam and more intake, single plane is there so he can spray the engine, when he gets the extra to buy a nos system. Lastly how but somebody put out a number instead of talking around the actual question!

11.0 to 1 per KB with .125 dome pistons and a 58 cc chamber.

 

Actually it is pretty much the same combo that mw66nova was running 13.0's with in his sc, just a little more cam and compression.

 

What a waste of money.

 

Thats just the old 350 is a better engine debate.

I do agree that the single plane intake, domed pistons, the octane requirement, and the cam are a waste of money.

A smaller cam, a dual plane performance intake, and flattop pistons with about 10:1 compression, would be faster. BTW, I believe KB rates their pistons at ZERO DECK, but the actual installed deck height will be around .020" in the hole. That combined with the typical .038" compressed head gasket as well as the 60 CC of the 416 heads (have CCd 3 stock pairs at about that) have the compression lower than you think.

1.5:1 roller rockers IMO are a waste as well. Could have atleast gone 1.6:1. I would have put the money into the port work on the heads instead.

We are having to talk around the question to find out what we need to take a guess at the power. I have anywhere between 275-350, the specifics are important as to the end guess.

I have a milder cam, lesser dual plane intake, TBI, NO headers, and was still able to pull down 270+ RWHP. More important is that I don't just have a high peak number. My torque curve looks like a table top. It is all in the combination, not just going big on everything.

Finally a cam in a 305 is no more radical than in a 350. The RPM for peak HP and peak TQ are very similar when the same cam is used. With a L82 corvette cam, my HP peak was at 5,200 RPM and peak torque was at 3,800. Right where the L82 made its power.

 

Not exactly the same 350 is better argument. More of the, why put that much money in something to go slower argument. I would definately disagree that a cam in a 305 is no more radical than in a 350. Those 45 cubes do make a difference.

 

If you want to go fast, why put your money in a Small Block?

The 45 cubic inches do make a difference, but not as much as you think. The RPM for peak HP and TQ stay ABOUT the same.

For example look at the GM Vortec 305/350. They use the same intake, same cam, same exhaust, same compression ratio, similar flowing heads, etc.

Guess what peak HP is at 4,600 RPM for both and peak torque is at 2,800 for both from the SAME cam.

 

That is a generalization made by GM. I dont think they will make a difference, i know. I have seen it done many times. Why do you think that a cam is more mild in a 400 than a 350? because of the 50 cubes. It makes a difference.

Why make silly arguments about small blocks? Sounds like someone wants to argue. Encourage more people to build 305's, it'll save all the 350s for the rest of us.

 

I know that they really don't make a difference. Yes the 400 will make more torque at the same RPM, but that is a function of displacement. The RPM will stay the same, I have dyno'd enough engines with the same "RV" cam to know. 305/350/400 with the old 204/214 grind cam, they ALL make peak HP @ about 4,800 and peak torque at about 3,200 @ the rear wheels furthermore they make virtually the same vacuum at idle, (about 20 in/hg @ 650 RPM). Now the peak#s vary widely, but the RPM stays the same. Therefore the cam is NO hotter or milder as displacement changes. I guess you could argue that the greater torque production makes the cam milder in a bigger engine although the power-band stays roughly the same.

Guess what, I build engines all day long. 305/350 there is so little difference when installed in the same car it is not even funny. I pulled a stock low-hour marine 260 HP 350 out of my boat(corrosion ate the head gaskets becuase the PO never flushed it out) and installed a HO spec 305 with the 350s highrise intake, Q-Jet carb, Exhaust, etc. The 350 would rap the speedo to 60 MPH at 5,300 RPM. Guess what the 305 will do, 58 MPH @ 5,200 RPM. IMO that is not as much difference as most will claim.

The marine 350 is on the stand to be rebuilt and go into my dads 1984 GMC 1-ton dually in place of a tired 6 MPG 454

 

Any performance build ought to include zero and square decking the block. That and try to shy away from the thick gaskets. Mine's zeroed and used .015" steel shim gaskets and with a touch uner 70cc chambers after porting and milling we're around 10.25.

agreed 100% on the dual plane intake and the rockers.

110 octane isn't going to do **** for you detonation wise if it's not tuned right, so be ready.

 

Guess what, so do I. Lets have an argument! Give me a break. If you believe that, fine. We are not talking about stock, or RV cams, we are talking about racing cams. Lots of overlap. These cams definately behave differently in smaller displacement engines.

My brother has a cam in a 283 that is on the edge of being comfortably driven. We have installed the same grind in 350's and observed dramaticaly different characteristics.

 

Let me add fuel to this. I had a 350 with AFR195 heads, Comp XR276HR cam, & Hooker longtubes in my Camaro. The car ran a best 1/4 time of 12.80 & had a fairly ragged idle. I then bought a 383 short block & swapped over the same heads, cam & headers. I richened the tune to compensate for the extra cubes. Guess what? The idle smoothed out considerably & the car ran 11.91. That only came from 33 more cubes. The cam actually had much better street manners in the 383.

 

Thanks for the input? I guess, just to let you know the deck was zeroed, I built the engine for someone else according to there specs, and they are happy with it, that is what matters, as far as the 305 vs. 350 debate, guess what? It's been going on long before this website was ever around for us to debate and it will keep going until there are no more of either left for us to build! I have also built 350's using a cam that was on the edge of street in a 305 and it had good street manners with the extra cubes, its simiple math. Anyone else have any good ideas on hp #'s since I have only heard 1, and thank you for at least giving a number even if it was a range.

 

I am fairly new to 3rd gens. I always had goldwing till I messed up my back, then I took up a new hobby. But if 350 are sooo much better then 305, why do I read about 305 with 160, 200, 225,000 miles and 350 being rebuilt with 40,000 miles. I say build those 350, keep Americans working, I'll be profiling in my 305 with 166,000 still laying rubber.

 

long live the 305!!!!!! Bring me your tired, weak kneed 350 and let me show you what a little mouse of a motor can do!!!

 

Your Right you are new

The only reason you probably hear about 350 blowing up is because the people who built them ****ed up

I have had plenty of high mileage small blocks 305/350..etc

 

Wow, thats one of the most silly things I have ever heard. So the 305 has better longevity now? You completely missed the entire point. The idea here is performance. Longevity is a non issue. This discussion isnt about longevity, the 305 and 350 are virtually identical in that respect. The only reason you hear about all those 350's blowing up is because people half-*** on a rebuild, or they just abuse the hell out of them. As fas as enjoying the 305, good. Thats what its all about. When it blows, stick a 350 in there and go faster.

 

Earlier my point was that when my 305 TBI blows I have a 454 TBI to put into mine that will be making around 500 HP when I build it, change the cam, heads, intake, and exhaust. Wasn't trying to be a smart *** on the getting rid of the small block, I am! Getting rid of the 700r4 too. In the process of building the 4L80E that came with the beast as well.



$400.00 for this 96,000 mile 454/4L80E/12 bolt 3.73/wrecked van combo.

I am tired of the low-15s. Looking at getting 5,300 lbs to run into the low 13s-high 12s.

 

lol, right on....... What good is a van if it can't run 12's?

 

this thread sucks. i cant believe people are arguing over this. "No replacement for displacement." end of story.

 

Fast...good luck waiting for that 305 to blow, and ljnowell..........long live Paul Bearer

 

I am thinking of turbo'ing the 305 soon. 375+ RWHP at 6 PSI of boost.