400-THE OTHER SBC (WITH DOUBLE BOOST)

when you mention the word small block chevy most guys think 350. some guys think 327 or maybe even 302 but chevy built a lot of other small blocks you know the other guys 262s 265s even 307s heck a 283 or a 305 so today we're going to look at one of the other guys one of the other small blocks i'm talking about the small block 400 and don't worry we even hit it with some boost let's talk a little bit about the small block 400 but before we do that in full disclosure the one that we use for this test was not actually a production block i did not go down to a wrecking yard and pick up a used 400 for this test i used an aftermarket block but almost everything that we did to this block you could do to a production block although we did exceed a thousand horsepower so that might be pushing the stock block just a little but let's talk about the 400 itself and the reason that it's not as popular as i think it should have been and the reason for that is some guys will tell you it's because of the rod ratio and we're going to get into that in a minute as i go off on a tangent but the real reason that the 400 was never as popular as a dz 302 or a 365 horse 327 or even the lt1 350 is that gm never did a performance version of that 400. if you took that 400 and applied all the stuff from the 365 horse 327 meaning the fuel the heads the 11 to 1 compression the duntov cam the high rise intake and the 780 holley the 400 would be the most powerful and the most popular small block gm ever produced that's because when it comes to power production bigger is better i'm going to go ahead and put up a shot here that shows you the difference in torque production between a dz 302 and the 365 horse 327 that video is up and you can take a look at that but if you look at the power difference between these two take a look at the torque down low so now magnify that by like 100 cubic inches which is the difference between the 302 and the 400 roughly i know it's 98 and i'm going to get comments about that but think about the extra torque that would be offered by the 400 i mean it could be 60 70 80 even 100 foot pounds of torque difference between those combinations now they might all make about the same peak power because the 302 the 327 and 350 basically all made around 350 or 360 horsepower and that's kind of a function of the cam timing and the cylinder head that we use which is a little bit limiting on this combination but a 400 with all that extra torque would have been one heck of a combination and why i think that the 400 might have been the most popular small block if gm ever did this let's check out our results before we get to our results i want to talk a little bit about rod ratio and this always comes up whenever i talk to anybody about the small block 400 because it had a shorter raw than the 350. and here's my response oh it had a the rod ratio is way worse that's why the thing didn't make power now we already went over why the thing didn't make power off 400 didn't make power because gm never equipped it with all the tools that needed to make power the rod ratio wasn't an issue and you might want to ask how do i know that well the reality is that rod ratio plays almost no part in power production at least in the range that we see of these normal street motors and most race motors now sure there are areas where guys take a look at this and they're looking for the nth degree kind of stuff and i'm talking about formula one and pro stock and and nascar and things like that but for what we do here for the a typical small block chevy the difference between the connecting rod length and the 400 and the connecting rod length and the 350 there's no power there there's none at all and i know this because i did a test not long ago when i ran the dz 302 and the l76 327 the lt1 350 i made the mistake of putting these motors together with a six-inch connecting rod and i put them all together the reason i did that is because the company that i was using for the pistons back then had shelf pistons ready to go that work with six inch rods because i needed to have different domes on all those different displacements to maintain the same 11-1 compression that we had to have for all those combinations so he had to have different pistons and they had them all readily available but they had readily available for six inch rods now i knew that it wasn't going to change anything when if i use that rod length but after i turned that story in we got a like barrage of comments and people telling me that the results are completely wrong they're not accurate this stuff is bogus this stuff doesn't work use a six inch rod that's going to completely change the power curve so i told the editor at the time i said look this doesn't make any difference but here's what i'm going to do i'm going to take one of these combinations and i'm going to put it together back together with a 5 7 connecting rod and i did just that basically all we had to do was get a piston and move the pin down we just had to change the compression height on the piston the the weight didn't change nothing else changed i put it back together with the 5.7 rod and all the same components same heads cam intake all that stuff and we put it back up on the dyno and the power numbers repeated exactly i'm talking about like i was surprised that it was that exact because if we take a motor off the dyno and and have it sit for two or three weeks and put it back on it might be off by a couple of horsepower but this was exact so it just tells me that that rod ratio change in that normal range had no effect on power at all that has nothing to do with why a 400 doesn't make power like the other 350 327 or 302 it just needed the other parts let's get to the results first test of our other guys smallbot 400 was to run it with an 871 supercharger you know make some boost on it because they all should have boost so our small block 400 was the speed master heavy duty block with their forged 4 inch stroker crank and 6 inch rods we also had forged pistons now those pistons produced a static impression of 8 or 11.25 to 1 which is fairly high for a supercharged motor but we can run boost on that compression ratio as long as we have enough octane which we did so we ran race gas now we installed a healthy comp cam in this thing it was a hydraulic roller cam but still a fairly healthy profile it was a cop extreme energy it was an xr 294 hr cam and that cam had a 540 562 lift split a 242 248 degree duration split and 110 degree lobe separation angle again hydraulic roller we topped this thing with enough cylinder head to feed a 400 inch small block set a dart pro 1 225 head so they were cnc ported and you know flowed plenty for this combination we also taught we also used a dart single plane intake a holley 950 ultra xp carburetor and instead of mentioned three quarter long tube headers and an msd distributor now equipped in this manner are 11 and a quarter to one small block 400 produced 575 horsepower and 513 foot-pounds of torque so as you can see 400 inches helps this thing make power you know bigger is always better but here's how we make it even bigger what we did was install the 871 and this was a yn 871 supercharger and ran a pulley configuration to produce a peak boost of about seven and a half pounds this was a 54 uh tooth bottom pulley and a 63 tooth top pulley and equipped with that at seven and a half pounds we produce you know 725 horsepower and 622 foot pounds of torque but obviously we were just getting started there and we also on the 871 supercharger we installed a pair of 950 carburetors on that to feed the supercharger we want to make sure we had enough airflow and fuel feeding our supercharger so then we made a pulley swap and went up and boost just a little bit i think on the seven and a half pound one we didn't do a lot of tuning on that because we knew that we were going to go up i think we could have straightened that curve out a little bit without any problem i think with that it got a little bit rich there so on our 8.7 pound one we change from a 63 top pulley to a 61 tooth pulley you know change the boost just a little bit but the tune was a little better on that 755 horsepower peak torque was 638 foot pounds then we finally stepped up to 11 and a half pounds and ran the motor out a little higher because the the boosted and the power was still climbing with this combination and we produced 820 horsepower and 665 foot pounds of torque so this was a good combination and again we ran race gas on it and this is getting up near the limit at this kind of boost level with no intercooler it would be good to have an intercooler at this boost level even though we were getting good charge cooling from the dual carburetors and that probably made it a lot more even like that this was a good combination it was a healthy small block 400 to begin with which we had a boost from an 871 we were kind of in the good power range for an 871 that's 800 horsepower range is good we've made as much as a thousand horsepower more with an 871 if you put it on the right kind of motor and are spinning it fast enough it will definitely make that kind of power and it'll definitely make more on this combination it's just that i don't like to get the charge temperature too hot in this combination especially with this high of static compression so now let's take a look we're going to take this same short block we're going to upgrade it a little bit and then add even more boost after subjecting our 400 to the 871 supercharger we made a few changes to the configuration these tests were run separately but i want to include them both in this video because there's some this is some cool stuff so we kept the short block the way that it was it was the speed master you know block with the forged internals but we changed the cam shaft and cylinder heads and the method of our boost so we put a set of trip flow super 23 heads on it but both those heads and the dart pro 1 heads both will supply plenty of power they both flow really well so both the heads are good but we did install a much bigger cam shaft in this thing in fact we installed a solid roller from the guys at bullet cams the cam was a 671 661 lift 264 to 70 degree duration split and 110 degree lobe separation angle so again it was a solid roller cam it was supposed to be an n a cam work well under boost too so the we had we retained the dart single plane intake manifold that we used previously but we did a little bit we spent a little bit of time tuning this thing we even used the spacer and tried a few tricks with the oil level and things and after spending a little bit of time on this combination it made good power produce 620 horsepower in a and 528 foot pounds of torque so this combination you know this thing was working really well that's the nice thing about having 400 inches and plenty of head flow plenty of cam shaft good intake you start out making good power so here's what happened after we installed a vortex supercharger so this first one we ran low boost and we ran a vortec t-trim supercharger we also replaced the holley 950 carburetor with a csu blow through 850 and obviously did the tuning on that as necessary so here's what happened when we ran low boost this is only six or seven pounds and we even cut this thing short at 6 700 rpm but it was still rising the boost was going up and the power was going up but we were up near 750 horsepower right away 746 and peak torque was at 617 foot-pounds of torque we knew this combination had plenty of strength and plenty of power potential so we stepped things up quite a bit after that because the bracketry for the vortec would accept a much bigger blower we installed one of the ysi superchargers because we figured this thing was going to go into the four digit level if we supplied enough boost and that's exactly what we did so we installed the ysi supercharger and as you can see the curve was still rising and we shut it off near 7000 rpm and we were up in the uh 1020 horsepower range with peak torque near 770 foot pounds of torque i'll go ahead and show you the boost curves um real quickly after these two and kind of show you what was happening with the boost but you know we more than doubled the boost pressure here or about doubled the boost pressure and made a lot more power we had a bigger blower more boost we had plenty of cubic inches we had an efficient n a motor to start with so that's going to make that's going to make good things happen let's take a look at the uh boost curves and then get to our conclusion right guys it's some of my favorite stuff i like checking out the boost curve supplied by the different blowers and the different combinations this is our t trim on our 400 inch small block blowing through that csu carburetor you can see in typical kind of centrifugal supercharger fashion we started out with low boost and it rises with rpm so we start out at 1.9 pounds at 3 000 rpm and we're up to 5.8 at 6 700 rpm and our pulley combinations for this we had a six inch blower pulley so i mean a six inch crank plate so not very big down at the bottom and a three point five inch blower pulley so we're not spending that teaching very fast as a matter of fact we've made a thousand horsepower with the t-trim and it will do that if you really push that thing but what we did was upgrade to the larger ysi supercharger to really get things going you know get the party started the nice thing is the bracketry will accept both of those superchargers so it was a simple blower swap which is pretty easy so here's the boost curve supplied by the ysi we started out at 7.1 pounds and rose to a peak of 15.9 pounds out here at 7000 rpm so that thing was ready to party now we have a couple things going on i don't have the crank blue we ran a cog setup on this and the blower pulley if i remember right was in the 50s oh no i just take that back a 32 tooth blower play we ran a cod drive on this so this thing was really spun up it was doing well we've made more than this with the ysi trim and it certainly will there was more boost left but we managed to you know break the four-digit power mark so it was pretty cool this is the booster supplied by our two combinations let's get to our conclusion okay guys here's your chance to make comments should i have used a production block i've gone down the wrecking yard and scoured all of them to try to find a small block 400 so i could use a production piece rather than using the thing from speedmaster now you could duplicate these these results with a factory block you could use that you could use like something like the one that i used from speedmaster get a dart block which is an awesome piece and we've done a ton of stuff with that but the reason that the 400 is so good is because it's 400 if you take this all of this stuff and apply it to a 350 it makes less power because a 350 isn't as much as a 400 and it's as simple as that now we we went off on a little bit on the the tangent on the rod ratio stuff but that's less important than the fact that a 400 has 50 extra cubic inches compared to a 302 so if you make something bigger and you're trying to reach a power goal it's much easier to do with extra cubic inches it just makes life easier and then when you combine that like we did with good cylinder heads and lots of camshaft and a good induction system then obviously when you top all that off with the icing that is boost everything works out great get a 400 add boost to it and good things are happening i'm richard holder guys thanks for watching make sure to like share subscribe ring the bell i'll keep testing

Channel: Richard Holdener

Views: 171,816

Keywords: SBC, 400, BOOST, SUPERCHARGER, 8-71, VORTECH, YS1, TFS, DART, BULLET, COMP CAMS

Id: 9uxBvY1Kyc0

Length: 16min 11sec (971 seconds)

Published: Sun Jun 28 2020