Hi Simon Glad you like the ramblings! Your ideas will work well indeed, I did a mildly modified standard valve head, just seat and throat work with std size ports & a Newman 268 cam to go on a std GTI 1800. It was also fitted with a Jetex system and an aftermarket manifold but not a great one. That made 132hp with a broad power spread and excellent bottom end and mid range power...better than some 2ltrs I've seen. If the RP is a low comp engine with deep dish pistons I'd probably replace them with GTi versions to get a better starting point for the C.R, or indeed the block can be skimmed to raise them like in the articles here and the head skimmed to get the C.R right for the cam. I'd guess you'll use the digifant system from a MK2 GTi? I've just done a 2ltr 8v on Digifant that made a touch over 150hp so it can work ok, but there are compromises, though a tamer cam than used would help and still make around 140hp as an 1800 with a good spread. Let us know how you get along with it and/or contact me if you need any help Simon.
Thank you for your reply and offer of help, Jason, very much appreciated. The results that you write about are perfect. I am not looking for out and out speed but more grunt and certainly better response with bottom and mid-range the focus. I have been doing some research regards my engine. As far as general concensus goes you are correct, the pistons are most likely dished giving the lower compression ratio, they certainly have their own product code to get replacements! from what I know and could find out online, the engine stacks up thus: 1,781cc; bore and stroke 81,0 by 86,4 mm; compression ratio 0,94:1 with a massive 90Bhp @5,200 rpm 105 lbft torque @ 3,000 rpm. Was a beast out of the factory for sure but "someone left the gate open" as they say over the fullness of time. I did a compression test the other day and the third cylinder is low on compression which certainly neccessitates an engine rebuild or at least an excuse to take it apart and have a look, which of course means rebuild with new pistons, sorted head, manifold, exhaust and a sportier cam! Thank you for the great advice here. I will source some standard GTi pistons if possible as I really like the idea of boosting the power but keeping the engine OEM and original. First I guess it would be best to strip the engine and check the bores are ok before ordering the pistons. I would like to fit a fast road cam, new tappets and valve guides etc and a vernier pulley if poss? Engine managment I was hoping to go with Megasquirt as I am looking to run that on my RX7 as well. Awesome, thanks so much for your help, I certainly will be in touch and probably start a thread here when I get going hey Simon
Hi Jason, Good to meet you yesterday, thanks for the advice ... and the future development of another `more valves`
Hi Andrew Likewise!....my grey matter has been working overtime since you left! Shh...don't mention "more valves"....I'll get lynched by the 8v massive! lol
A slight change of direction... I'm often asked about my own projects, my usual answer is "if only I could find the time"! Well as soon as I can here are a few waiting in the wings... I've had this laying around a while...couple of years actually. As can be seen it's a very early 8v Mk2 GTi, saved from a friend in the trade who break's them. It runs quite well with a healthy engine, has the original red/orange stripe interior, but a nasty o'l 80's glass sunroof...I guess a roof skin may sort that at some point. It cleans up ok-ish but needs a few scabby bits sorting, could make an ok resto at some point with some period mods...head work, 1900 bottom end etc...time will tell. Continuing with the white MK2 theme... This H-plate big bumber will be a daily driver at some point soon hopefully. It came as a non runner...I expect the trailer gave that away!...but a new fuel pump sorted that. Power is via 8v's on std digi injection but has had a 2ltr block fitted with all else standard. The exterior is tidy after a fairly recent re spray, and I've re fitted some of the interior. Engine runs well and should make a good base for some head and cam work experiments, and the lecky windows, P/S & factory sunroof should make for reasonable road transport. And just in case there isn't enough MK2 action going on... This came along via a customer who's dad was on the move and needed it shifting....well it would have been rude to say no thanks. It's log booked as a rally car and has a basic roll cage & perspex, a spare set of Leda dampers & springs in need of an overhaul and a blank canvas courtesy of an empty engine bay!...well actually it came with the 8v it used to run with a ported head & GS2 cam but that wont be going back in. Long term it will be home to some 16v development but may have the MK1 hillclimber 8v fitted short term. It's stomping ground may include some hillclimb use but the main plan is to get out to play in selected rounds with my VAG trophy customers...class B at first maybe but ultimately class A...time will tell
Time for a catch up... We've done some work on Tim Hughes MK2 before, a lower F/D swap & a Quaife diff, along with a tailbox swap from the previous poor design which netted a 7hp peak power gain and 13hp (yep 1 & 3!) gain at mid range peak torque rpm. Looking at the power curve the last time I saw the car, the way it levelled off between peak torque and peak power was telling me the engine was struggling to breathe as the revs rose. The engine was also down on power overall considering the spec (110 at the wheels..133-134 at the flywheel), so my suggestion was I take a look at the head and see what we had to start with and look at improving the flow. The previous owner, a friend of Tim's, had an engine kit supplied and fitted along with, as we discovered, a 40.5 / 35mm head. I've always seen improvements with these with some re porting, but as we wanted to get the 2ltr breathing properly my suggestion was we kept with the 35mm exhaust valve but re port and add 42mm inlets. Now to cut a very long story short, as I opened the last inlet throat it cracked through...I've gone much bigger without an issue so this casting must have just been a bit thin, nothing my alloy welder guru cant fix...normally! After 3 attempts at grinding out and re welding it just wouldn't take as the pressure test showed...it can happen but its rare...so with time very much not on my side I started from scratch with another casting. Now we had a dilemma, or at least Tim did as I was confident I knew the answer. Tim had a budget (as we all do) to fit the bigger inlet valves & new inserts it needed as we were going to do on the original head, but bigger inserts to support the 35mm exhaust valves from the old head wasn't in the plan. It was simple in my head (pardon the pun!), we'll just use the 42mm inlets as intended but keep to the std 33mm exhaust valves. Tim had some reservations about my 42 / 33 combo as the word on the street says a 2ltr needs a 35mm exhaust valve to make power. I politely pointed out that his name sakes (Tim Moll's) 2ltr race spec 8v crossflow made almost 200hp on 33mm exhaust valves so I wasn't too phased about hitting the target I wanted to see of around 150hp. While the head was off Tim measured the piston deck height for me so I could work out what needed skimming off the head to get the C.R right. It was then we discovered 2 more reasons for the engines lack of sparkle...the pistons were too far away from the block deck for decent squish, which in turn, along with the deep piston bowl, contributed to the C.R being roughly 1-1/2 points lower than ideal for the 276 cam used. With no perfect solution, I roughly closed the C.R deficit down by half by skimming the head as much as I dared with a view to maybe sorting the block at some point. The new 42 / 33 ported head was then sent back to Tim for re fitting, followed by the car heading back down to us to run up on the rollers for fine tweaking. However, at the end of the one and only power run, the rattle from the bottom end told me we would be looking at the rest of the engine sooner than planned! To cut another long story short, Tim left the car with us and returned a couple of weeks later to remove the engine for me to look inside. As I suspected, number 3 big end had gone, resulting in a scrapped crank and rod. With a replacement crank found and some rods I had going spare that we fitted with ARP bolts, I re built the engine after correcting the squish & compression short fall while it was apart with a good skim of the block. After Tim returned to fit the engine, it fired up instantly for us to take straight over to the rollers to finish what we started once and for all. With time yet again not on our side, I bedded the rings and bearings in during the 5 mile drive to the rollers to see how much all the effort was worth....would we get close to our 150hp target, would we gain any more mid range? Well it certainly felt a bit stronger on the road, but with the ignition and fueling set at a conservative estimate I didn't push my luck too much. After some more running on the rollers and some basic setting up the fresh engine was much more responsive than the old, almost "open induction" like in throttle response...not bad for digifant! So the moment of truth had arrived...what would the so called wrong valve size combo give us...the answer was more power...everywhere. With 4 to 5hp more at 3 to 4000, peak torque rpm was next up...an extra 10hp & 4500 from the new combo wasn't to be sniffed at. With the old engine/head, power started to flatten out shortly after peak torque, but not anymore. With power now climbing much better than before we had an extra 12hp @ 5000, 13hp more at 5500 and peak was now 17hp up over the previous best @ 6K, with 127 at the wheels, around 152-153 at the flywheel, with power at 6500 10hp up too. With the car un-strapped from the rollers and a quick (quite literally!) run up the road completed, I brought the car back for Tim to try his new power unit....the grin on his face upon returning said it all. I feel there could be a little more to come as time didn't permit any inlet manifold/plenum porting at all, but for now Tim's 2ltr 8v is making the power it always should have. The graph shows the progress from as we first saw it, the tailbox change, and finally the current spec with the new head & improved squish & C.R.
This ties up with race mini experience eon's ago. I used to run full race offset valve longman heads, but dropped a valve at an event. (autocross) In the ensuing panic (chasing championship points) I had to build another engine quickly. I had a very similar head spare with 2mm smaller exhaust valves. On it went, and more torque and a couple of more geegee's, at a slightly lower rpm. Cam used was supposed to be a slightly inferior type also, so not quite comparing apples with apples. Still a surprising result. Dyno's shouldn't lie! Jon The offset valve engine would hold peak power further up (8000+!) though, an important feature racing on grass
It's coming along nicely Timothy.... That's the 3rd "small" exhaust valve engine (in relation to the inlet size) I've done now Jon...the ones mentioned above plus a 170hp 1800. Getting the air in is the hard bit, getting it out is fairly simple providing there isn't a cork in the exhaust like the car had when I first saw it. I've never been able to work out the big exhaust valve rule for 2ltrs...the best I can see is it goes back to early tuning of these engines when there wasn't so much testing and the general thought was exhaust flow needed to be a much higher percentage than it actually does to expel the dead stuff...the "sheep" factor then followed and it went on from there. There's no doubt that bigger exhaust valves can help on an engine that could benefit from it when maximum power is being looked for, like a race engine on 42mm inlets for example, but in general terms it's the inlet that's the most important side. For most road application the std 40/33 size is fine. For the first upgrade a 40.5 valve will fit on the std inlet seat and show a positive flow gain when ported to suit. After that a bigger inlet valve is the way forward, but that calls for a bigger seat so the cost jumps up. Following on from that, the correct size exhaust valve if budget permits and the spec really needs it.
And just to prove we're not totally 8v biased!.... Mark Liney came to me via various recommendations. He had been struggling to get results from his circuit race MK2 with ABF power. Mark had spent his hard earned on some DTH Jenvey bodies and Omex management and only gained 4hp over the std plenum. So after one too many Clio 172's had passed him on track Mark came looking for a solution. His original request was for a ported head and some decent cams to enable him to reach the 175hp at the hub's his power to weight target permitted, and as he was only 15hp shy it wasn't going to be too difficult. My original plan was to have some custom cams ground to suit and see how close we could get to the target as a std ABF head flows enough for 200hp, and combined with the ITB's I wanted to see how little port work was needed to top up the rest based on the powerband I wanted to achieve...as the class is power to weight restricted I wanted to keep the torque up as much as possible, so keeping the port sizes down would help...only making them as big as they really needed to be. However, during a chat with Mark when he dropped the car off he said some tame road cams had been fitted in an attempt to help the power which they did as he certainly noticed the difference...the car was noticeably slower! So the o'l grey matter kicked in again and I figured a look in a different direction was now worth a try. After quizzing Mark he told me the cams had been fitted by a VW specialist so he assumed the timing was right but they just didn't suit his set up, but being tame 260 hydraulic profiles I was confident in what I was going to find if he "just let me check the cam timing to be sure"... Upon removing the bonnet there was also something else obvious...how was the engine getting a decent supply of cool air with the radiator filling the front panel...with the grey matter now smoking away I had another idea. While I was having a poke around I popped off the air filter to measure up the trumpet lengths and found a throttle linkage hanging loose but working...hmm. I wanted to run the car in an "as delivered/last raced" condition so it was off to the rollers a couple of days later, which highlighted the reason Mark had been struggling on track when 139hp at the wheels popped up on the dyno screen. Standard ABF's on the AP Motorsport rollers show low 130's normally so with Mark only seeing 4hp from the ITB's the puzzle pieces where falling into place. Alvin at AP thought I was packing up early when I dropped the bonnet back into place...oh no..."run it again"!....132 at the wheels!....a 7hp loss because the engine now had no source of cool air due to the rad location. Not wanting to drive the car back with the loose linkage I re secured it but it was evident we weren't getting full throttle either...so with that fixed we did another power run...it's surprising how easy it is to find another 7hp at peak power, plus a decent amount right through, just from opening the throttles all the way! Back over at the JMR workshop I stripped the slam panel off for a better look and figure out how we were going to drop the rad down...easy enough...remove the crossmember it sat on and lower it into the bumper area where there was plenty of cold air feed available, with the grill area taking care of the rest and a decent size gap now available to feed the new inlet set up I had planned. A check of the cam timing while at the workshop revealed what I suspected...badly set cam timing...actually very badly!....with 1 thou lift at TDC on the inlet and 34 thou on the exhaust the timing was retarded and badly phased...so armed with my trusty TDC finder and a dial gauge it was back to the rollers. A quick run to check the power again on the day and give me a starting datum point gave a direct comparison for the next run a while later with the revised cam timing...I gave the exhaust a touch more to bring it up to 43 thou and the inlet a lot more to make 65 thou, so we now had much better phasing and advanced timing. With Alvin turning the rollers once more we had a 1hp loss at 2000...shock horror!...but I was confident that would probably be the last we would see. From 2,500 up the cam timing re set gave an extra 3hp minimum, through to between 11 & 8hp from 4,500 to 6k, and back to 3hp extra at peak...but now with a leaner mixture as the engine was pulling in more air. Some extra fuel added another couple of hp to peak, as did more ignition timing, where we ended with 155 at the wheels...so far so good, but the inlet length was still too short so back to the workshop for the next phase. The extra length I wanted to run meant "bending" the trumpets forward...not literally obviously, but with some curved extensions that I had a very clever fabricator make up for me. These both tipped the trumpets forward and would add an extra 35mm to the final length I wanted to run along with the 120mm trumpets...so back to the rollers one last time. With the original 90mm trumpets fitted to the curved extensions we had some small but positive gains at the low end and some worthwhile (6-7hp) gains at both the mid range and nearer to peak, plus a couple more hp at the top. Last but not least the 120mm trumpets were fitted. Another couple of hp was gained at the low end but with a couple lost in the mid. Alvin was game to swap them back but I wanted to keep going...good job too...there was another 9hp to come at 5500rpm, +7 @ 6k and an extra 5hp at 6500, plus a couple more again at the very top of the power band. We swapped between the 90 & 120mm trumpets to see if there was any fluke readings going on, and the shorter trumpets did indeed give a better result at a couple of mid range points but I elected to run with the longer ones as there were more gains than losses, and the engine had a much more noticeable "bark" on the 120mm trumpets, so its certainly drawing harder. All in all we ended with a peak of 162 at the wheels from our 139 starting point (though I believe Mark was racing with less than that due to under bonnet temps) and holding 161 @ 7k. The right induction length can clearly pay dividends, but so can details like temp and really simple things obviously like throttle operation. And as for cam timing...I'll reserve judgement in print of the specialist Mark had fit and "time" them. So if you have performance cams fitted and the results are less than pleasing you now know one of the reasons why. As for this project, there are plans for a much better exhaust manifold as I suspect the current ebay "shiny special" with it's short primaries being a part of the mid range drop, plus it wont work at all with the new cam specs....watch this space! Oh almost forgot....Mark ran the car back on the designated hub dyno 2 days later where they agreed with the sub 34ibft mid range increase but said there was only a 4hp peak gain rather than the 20+ I'd seen...go figure on that one! Mark said the most important thing is what the lap times tell him, I guess 12 seconds a lap faster (in traffic!) at Snetterton says it has more than 4hp to me. The Clio's were still a problem, blocking Mark's vision in his rear view mirror () as he cut through the traffic from a slippery qualifying position at the back of the grid to end up involved in a minor shunt...Mark claiming he now needs much better brakes with the extra power to slow down! And finally....the real net gain from the above....
A massive thanks from me to Jason and Alvin.......they have gone out of their way and put in the hours as well as free rented workshop space and tools over the last 2 years or so putting right bad workmanship from a famous builder/tuner of VAG machinery.......a blocked exhaust, a cam not bedded in properly, bad squish and wrong CR, a less than optimal big valve head(exh), pistons from VW Brazil not KS as advertised, a badly built bottom end which did not spin as freely as it should, un-known bearings etc etc ......i can tell you i was relieved when Jason covered up the blue block with a nice shade of grey for me( i havent quite earned orange block status yet as existing pistons and rings were used in the un-scheduled bottom end rebuild......maybe one day eh Jason). I now have confidence in the engine again after Jason has fettled with a fully balanced bottom end with correct cr and squish for the cam (newman 276), and of course the unscheduled head rework after original collapsed.........sporting nice shiny stainless REC 42mm inlets now with proof that big ex valves are NOT the pre-requisite of power in an 8v. The figures speak for themselves.......from 103 atw as built by the blue blockers out there to 127 atw (153 ish bhp atf) .....with a shiny grey block....... Jason feels a little more is poss with an ECU change and a custom plenum......it certainly feels very lively on the hills now with confidence restored......although this season was pretty much spent in a workshop.....albeit a welcoming one. The past is past and lessons learned.....take what you will from my experiences above and beware!........the old school skill and know how to build these engines is out there but shop wisely........i do now........JMR are the only 3 letters in my phonebook now. Jason forgot to mention the chinese puzzle cv joint conundrum we had too whilst Alvin patiently waited at AP HQ on the eve of his summer holiday!! lol
A bit of a follow on from Tim's car above. .tho one I've been waiting to write about for 7 years! When my best mate (tones61) said his old engine was getting a bit tired in his GTi and he was planning a 2ltr swap I volunteered to do a ported head for it. I'd built many engines..from std road to lairy hillclimb..over 25 years in the motor trade previous to this and ported a couple of heads for old mini's and fords, but no VW heads from scratch..."how hard could it be"! So armed with my trusty die grinder I set about my first Golf head. I was confident enough to know the basic engineering principles I was applying would (should) give the result I was looking for so as well as the head I did the article that made sticky status in the 8v section. .so thanks to all those believer's way back then! Fast forward to 2015...and a picture I've been waiting many long years to take and show... ...on the rollers at last! I say at last because Tony never felt the need or rush to quantify it's power output as he always use to say..."goes alright! ..so no rush"! Now that coming from a Civic type R owner at the same time as having the Golf plus various 600cc bikes during the period said enough for me. I remember asking Tony not long after it was running if it ever felt slow using the Golf after the type R...with a 50 ish hp difference. ."not at all" was the answer.."the Golf would murder the Honda around town"!...brave words, but the owners always right I say...well sometimes they are!lol So after finally getting the keys in my possession and getting the chance to drive it "properly"..I'd only ever run it round the block before...I got what Tony meant...it 's quite lively for a road spec 8v! After finally saying goodbye to a faithful old friend in the shape of a 306 rallye recently I was expecting the Golf to feel a bit lacking...the Peugeot had a ported head too so was a quick ol thing...would the Golf stack up or would I be looking for some 45's soon! With more than enough on road performance I figured a quick trip to the rollers at AP Motorsport was in order to see what we had... As can be seen in the graph the principles apear to work. . .the headline number is 125hp at the wheels. .around the 150hp at the flywheel the spec always should have made...phew! Now I had nothing to do with the bottom end at all...Tony is a very capable mechanic so built that up himself. .all I did was the head and cam spec. The head still runs std valve sizes. .and good ol K-jet injection. I say good ol but at times it can get a little jerky in nose to tail traffic...Tony was always right in saying "you wouldn't really want to run more cam on the road"...284 duration gives more than enough grunt on the road. In fact looking at the numbers in the mid range tells a story...110 at the wheels @4500 is a good bit more than any plenum equipped 2ltr 16v Golf I've seen on the same rollers...only Tim Hughes similar spec engine beats it for a plenum car @ 113hp at the same revs...in fact both our engines better the best ABF powered cars I've seen to date up to 6000...after that to be fair the 16v advantage takes off...but only when the 8v's start to struggle. .and even then only by 10hp in terms of peak numbers. .8v torques anyone?! At some point I'll get it back on the rollers to check the fueling and swing the cam timing. .it's only just a bit advanced at tdc on the inlet. .so we'll see if any more can be squeezed before its maiden track day debut at Curborough next month. In the mean time I'm surfing the 8v wave!lol
