Sotenacious Posted January 1, 2013 Share Posted January 1, 2013 Hello fellow z owners i would like to see how much horse power i would be looking ad with an engine of these specs. >l28 >n42 head, ported polished, Lift(In/Ex): .560/.560. Duration(In/Ex): 300/300, kameari big valves >n42 block, ross forged 1mm over high comp pistons, 1mm head gasket >kameari high performance oil pump >later electronic distributer from 280zx >ztherapy su carbs >msa 6-1 headers 2.5" exhaust system Engine will also be about a 10.5:1 compression ratio Quote Link to comment Share on other sites More sharing options...
BlueStag Posted January 1, 2013 Share Posted January 1, 2013 (edited) Hello fellow z owners i would like to see how much horse power i would be looking ad with an engine of these specs. >l28 >n42 head, ported polished, Lift(In/Ex): .560/.560. Duration(In/Ex): 300/300, kameari big valves >n42 block, ross forged 1mm over high comp pistons, 1mm head gasket >kameari high performance oil pump >later electronic distributer from 280zx >ztherapy su carbs >msa 6-1 headers 2.5" exhaust system Engine will also be about a 10.5:1 compression ratio About 165hp? I think you will find a very similar engine described here: http://datsunzgarage.com/dyno/index.htm Edited January 1, 2013 by BlueStag Quote Link to comment Share on other sites More sharing options...
BlueStag Posted January 1, 2013 Share Posted January 1, 2013 From elsewhere on the site: "Detailed experiences online show that modified SU carbureted L28s on 93 octane seem to max out around 160-170 at the rear wheels (210 hp flywheel)." Essentially a NA 2.8L with SU's will be doing good to put 165hp to the wheels. Quote Link to comment Share on other sites More sharing options...
Xnke Posted January 1, 2013 Share Posted January 1, 2013 Norm the 12 second SU Dude (Yep, he's real) was running an S30 into the 12's on SUs...that takes a little more than 165HP. Strokers have put down around 220HP, sometimes more, on SU's, too. They can flow enough air and enough fuel to support more than that, but I am not sure how much more. It is not possible for us to make an accurate estimate on your engine build. Not enough information given, nor is every engine built to the same specification going to put down the same power. Quote Link to comment Share on other sites More sharing options...
PMC raceengines Posted January 2, 2013 Share Posted January 2, 2013 Blue stag your right on the money ,, yes there are men out there that have pushed the twin carbs but ,, there not normal carbs when there done , stock carbs 200hp engine will pull you up , Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted January 2, 2013 Share Posted January 2, 2013 Yeah the most I've seen in person is 196rwhp from some twim SU's. He had an amazing port job and was bored 40 over, but for the most part it was all very stock. He made power from 6-7kr rpm. His carbs only had some other needles if I remember. He did not have to bore them out like what some people do. 1 Quote Link to comment Share on other sites More sharing options...
johnc Posted January 2, 2013 Share Posted January 2, 2013 Cars built to SCCA's E Production rule set are limited to the stock diameter SUs, 12 to 1 CR, .500 lift cam, and 2.4L. They can make up to 240hp but they spin them pretty high. Quote Link to comment Share on other sites More sharing options...
Gollum Posted January 3, 2013 Share Posted January 3, 2013 Cars built to SCCA's E Production rule set are limited to the stock diameter SUs, 12 to 1 CR, .500 lift cam, and 2.4L. They can make up to 240hp but they spin them pretty high. There ya go people, it's not a hard equation. HP = Torque X RPM (divide for scale conversion) You want power? Increase torque. How much you add where is going to tell you exactly how much power you're going to make. Like JohnC says, there ARE people out there making absurd power on SU's, but they're only running SU's because of class limitations. You can bet your monkey's uncle that if they could swap to something else then they would. I personally feel the most reliable way to get power is to call someone who knows what they're actually doing. Having a head built by someone with extensive datsun experience will usually turn up good results. The head is where the power is at, and it doesn't need to break the bank. $2k goes a LONG way with most head builders in getting a hot street head built, and honestly, isn't more than american V8 guys spend on their heads. Also: I see you've done some "shopping" which can be absolutely useless sometimes. You spec things like the kameari oil pump, msa header, ztherapy SU's, all of which are just throwing money away in my opinion. Stock oil pumps are great, turbo oil pumps are even better, and hell I've got one sitting on my shelf that makes a tempting door stop. Header options are almost limitless and the MSA one isn't all that special and it's generally agreed upon those actually MAKING the power, that too many people look for power in the header that just isn't there. And to be honest, I've always felt that the ztherapy su's are a bit of a show piece for the people wanting an "all original" 240Z show car. They have little value in my world of budget hot rodding. This is not meant to be an attack on ztherap, on the contrary, I think they charge a fair price for their service, but on the other hand there's a lot of other options out there for the performance minded. And one last note. If you want to run 10+:1 compression you're going to want something better than just the 280ZX dizzy. Do yourself a favor and get something that's programmable, and preferably multiple coils. One of the biggest upgrades you can make to an older engine is to upgrade the ignition to something with a controllable curve, and has a lot more energy. And high RPM is where the power is at, and you'll want a spark system up to the task. In many cases you'll end up needing to pull timing in trouble spots to prevent detonation, which simply can't be done without a computer controlling spark. And of course, all this information would have been at your fingertips... had you searched... Quote Link to comment Share on other sites More sharing options...
BlueStag Posted January 3, 2013 Share Posted January 3, 2013 "This is not meant to be an attack on ztherap, on the contrary, I think they charge a fair price for their service, but on the other hand there's a lot of other options out there for the performance minded." Perfectly correct. I am running currently a pair of SU's on my Triumph Stag with a Z engine because it looks British to do so. Frankly, I would be persuaded to go to fuel injection or even better a turbo when next money rains from the sky. The THING TO KNOW about the ztherapy carbs is that they have beat the leaky throttle shaft utterly. SU's with leaky throttle shafts are impossible to tune. What you pay for is real engineering of the throttle shaft. And damned well worth having. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 3, 2013 Share Posted January 3, 2013 Norm the 12 second SU Dude (Yep, he's real) was running an S30 into the 12's on SUs...that takes a little more than 165HP. Strokers have put down around 220HP, sometimes more, on SU's, too. They can flow enough air and enough fuel to support more than that, but I am not sure how much more. It is not possible for us to make an accurate estimate on your engine build. Not enough information given, nor is every engine built to the same specification going to put down the same power. Norm's was a stroker, turning over 7,000 rpms, and the SU's WERE NOWHERE NEAR a set of 'Z-Therapy Rebuilds'! You use stock SU's you limit the power. You can get more, but using stock bore SU's limits unless you spin the hell out of it...and mixture control at idle won't be that great... Quote Link to comment Share on other sites More sharing options...
BlueStag Posted January 4, 2013 Share Posted January 4, 2013 Fundamentally, if you use SUs and put more that 175hp to the ground you are really accomplishing something. Quote Link to comment Share on other sites More sharing options...
Z Greek Posted January 4, 2013 Share Posted January 4, 2013 I put together a 2.8 last summer that put 178hp to the ground on a brand new Dynojet 24. Very close to stock. Cam is .475 lift, 224 @.050 duration, 109 LCA (Isky "stage 1" street cam, 9.65:1 compression (flat top pistons, P79 with 49.5cc combustion chambers), cast pistons (1mm over), good three angle valve job with seats blended pretty nicely, SU's, stock airbox, pistons all set at exactly .010 "out of the hole", balanced, and a really crummy old header that I pulled off of a car at the local pull and save (I used the header mostly to save weight compared to cast manifold, I doubt it gained me anything). I received some great tips from Peter at PMC race engines that I employed, but mostly just lots of attention to detail. I have WAY less than $1,000 into this engine (I'd have to add it up, but probably around $800), and it currently has 45 race hours on it, and going strong. It does not have to be complicated, or expensive. I attached my dyno runs if anyone is interested. All_Runs_Data L28 version 2.0.pdf Quote Link to comment Share on other sites More sharing options...
BlueStag Posted January 4, 2013 Share Posted January 4, 2013 I put together a 2.8 last summer that put 178hp to the ground.... I have WAY less than $1,000 into this engine (I'd have to add it up, but probably around $800), and it currently has 45 race hours on it, and going strong. It does not have to be complicated, or expensive. Wow. I am inclined to believe this is a standard to beat. Pretty reasonable compression, what sort of octane do you run? Peak HP at about 6000? Not bad. Mine is definitely a road car. I cannot dream of an engine that spins regularly to 7000, just not part of the plan. I really like this mix. Lots of power for the money. Quote Link to comment Share on other sites More sharing options...
Xnke Posted January 5, 2013 Share Posted January 5, 2013 Mine is my daily, and sees 7000RPM every time I get in it. It's all about gearing. Quote Link to comment Share on other sites More sharing options...
Z Greek Posted January 5, 2013 Share Posted January 5, 2013 (edited) Wow. I am inclined to believe this is a standard to beat. Pretty reasonable compression, what sort of octane do you run? Peak HP at about 6000? Not bad. Mine is definitely a road car. I cannot dream of an engine that spins regularly to 7000, just not part of the plan. I really like this mix. Lots of power for the money. Thanks, I was really happy with the way it turned out. I don't know about standard to beat, but it's a pretty good engine. Peter at PMC has told me about some stock engines he has built that made a lot more power than this. 170 whp was my goal, and I would have been happy with 160, so 178 was over the top. My buddies ran their Datsun Roadster with a N/A SR20 in it the same day on the same dyno, and made around 146 whp (and they have podium'd 5 times with that car, including 4 checkers). This same car (the roadster) made over 160 on another local chassis dyno. As we all know, any chassis dyno is only good for relative measurements. I feel back to back runs comparing my engine to the roadster engine was relevant. I run nothing better than pump premium, and 35 degrees total advance. You can see the A/F numbers on the dyno run data. I am going to try some different needles next year to try to get some of that mid-range richness out of it. Last year this engine ran with a welded 3.9 diff., this year I will be running a welded 4.11, so I may try a cam to move the power band up 2-300 rpm. I am building a new car this winter for next season (74 260 I bought for parts last year). The race for next season on my home track was just announced, it will be a 36 hour enduro. Starts at 9pm Friday July 5th, checker drops 9am Sunday the 7th. Should be a blast! I posted a short video of the engine on the run-in stand last summer. Also posted a picture of the car as it sits right now. It's coming along, but July will be here before you know it! Edited January 5, 2013 by Z Greek Quote Link to comment Share on other sites More sharing options...
BlueStag Posted January 5, 2013 Share Posted January 5, 2013 I'd be thrilled to have 175 hp from what is basically a very slightly tweeked engine. You prove the point made earlier that spending money is not necessarily the path to success. Lots of gear gets bought that does little or nothing to make an engine run. Quote Link to comment Share on other sites More sharing options...
PMC raceengines Posted January 5, 2013 Share Posted January 5, 2013 One of the key things with Z Greeks combo is the cam 224 @50 if you step over 230 @ 50 the carbs dont work as well , and kills torque , right where you need it with the stock carbs. I built a stock flat top 86mm bore N42 head with all stock parts just a small port job , stock valves but i payed lots of atenchion to the seats and shape of the valve . Also spent lots of time on rocker geometry making shore i had every bit of lift the stock cam had , the bottom end was stock with 2.3 th on all bearings i spent many hours geting the crank to spin with a flick of my fingers . Exhaust was 2.5 in and the pipes were just of the shelf cheep things , after tuning it made 208hp engine and was a cracker to drive , only down side it was not easy to get much timing in with the N42 with flat tops and stock cam , timing was 28 total on pump 95 fuel , .. Other race engines with stock 240 carbs we have done made 240hp but fell over so hard at 5700 , this was a class winning engine , after he left the class we fitted 44mm solex carbs and the engine went 289hp Quote Link to comment Share on other sites More sharing options...
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